Many of the members of the sub-family Hydrophilides construct egg-cocoons.

In the case of _Hydrophilus piceus_, the {218}boat-like structure is

provided with a little mast, which is supposed by some to be for the

purpose of securing air for the eggs. _Helochares_ and _Spercheus_ (Fig.

100) carry the cocoon of eggs attached to their own bodies. _Philydrus_

constructs, one after the other, a number of these egg-bags, each

containing about fifteen eggs, and fixes each bag to the leaf of some

aquatic plant; the larvae as a rule hatch speedily, so that the advantage

of the bag is somewhat problematic.

[Illustration: Fig. 100.—_Spercheus emarginatus_ ♀. Britain. A, Upper

surface of beetle; B, under surface of abdomen, with the egg-sac ruptured

and some of the eggs escaping.]

The larvae of the aquatic division of the family have been to a certain

extent studied by Schiödte and others; those of the Sphaeridiides—the

terrestrial group of the family—are but little known. All the larvae seem

to be predaceous and carnivorous, even when the imago is of

vegetable-feeding habits; and Duméril states that in _Hydrous caraboides_

the alimentary canal undergoes a great change at the period of

metamorphosis, becoming very elongate in the adult, though in the larva it

was short. The legs are never so well developed as they are in the

Adephaga, the tarsi being merely claw-like or altogether wanting; the

mandibles are never suctorial. The respiratory arrangements show much

diversity. In most of the Hydrophilides the process is carried on by a pair

of terminal spiracles on the eighth abdominal segment, as in Dytiscidae,

and these are either exposed or placed in a respiratory chamber. In

_Berosus_ the terminal stigmata are obsolete, and the sides of the body

bear long branchial filaments. Cussac says that in _Spercheus_ (Fig. 101)

there are seven pairs of abdominal spiracles, and that the larva breathes

by presenting these to the air;[98] but Schiödte states that in this form

there are neither thoracic nor abdominal spiracles, except a pair placed in

a respiratory chamber on the eighth segment of the abdomen, after the

manner described by Miall as existing in _Hydrobius_. No doubt Cussac was

wrong in supposing the peculiar lateral abdominal processes to be

{219}stigmatiferous. In _Berosus_ there are patches of aëriferous, minute

pubescence on the body. The pupae of Hydrophilides repose on the dorsal

surface, which is protected by spinous processes on the pronotum, and on

the sides of the abdomen.

We have already remarked that this is one of the most neglected of the

families of Coleoptera, and its classification is not satisfactory. It is

usually divided into Hydrophilides and Sphaeridiides. The Sphaeridiides are

in large part terrestrial, but their separation from the purely aquatic

Hydrophilides cannot be maintained on any grounds yet pointed out.

Altogether about 1000 species of Hydrophilidae are known, but this probably

is not a tenth part of those existing. In Britain we have nearly ninety

species. Some taxonomists treat the family as a series with the name

Palpicornia. The series Philhydrida of older authors included these Insects

and the Parnidae and Heteroceridae.

[Illustration: Fig. 101—Larva of _Spercheus emarginatus_. (After

Schiödte).]

FAM. 13. PLATYPSYLLIDAE.—This consists of a single species. It will be

readily recognised from Fig. 102, attention being given to the peculiar

antennae, and to the fact that the mentum is trilobed behind. This curious

species has been found only on the beaver. It was first found by Ritsema on

American beavers (_Castor canadensis_) in the Zoological Gardens at

Amsterdam, but it has since been found on wild beavers in the Rhone in

France; in America it appears to be commonly distributed on these animals

from Alaska to Texas. It is very remarkable that a wingless parasite of

this kind should be found in both hemispheres. The Insect was considered by

Westwood to be a separate Order called Achreioptera, but there can be no

doubt that it is a beetle. It is also admitted that it shows some points of

resemblance with Mallophaga, the habits of which are similar. Its

Coleopterous nature is confirmed by the larva, which has been described by

both Horn and Riley.[99] Little is known as to the food and life-history.

Horn states that the eggs are placed on {220}the skin of the beaver amongst

the densest hair; the larvae move with a sinuous motion, like those of

Staphylinidae. It has been suggested that the Insect feeds on an Acarid,

_Schizocarpus mingaudi_; others have supposed that it eats scales of

epithelium or hairs of the beaver.

[Illustration: Fig. 102—_Platypsyllus castoris._ A, Upper side; B, lower

side, with legs of one side removed; C, antenna. (After Westwood.)]

[Illustration: Fig. 103—_Leptinus testaceus._ Britain.]

FAM. 14. LEPTINIDAE.—_Antennae rather long, eleven-jointed, without club,

but a little thicker at the extremity. Eyes absent or imperfect. Tarsi

five-jointed. Elytra quite covering abdomen. Mentum with the posterior

angles spinously prolonged._ A family of only two genera and two species.

Their natural history is obscure, but is apparently of an anomalous nature;

the inference that may be drawn from the little that is known being that

they are parasitic on mammals. There is little or nothing in their

structure to indicate this, except the condition of blindness; and until

recently the Insects were classified amongst Silphidae. _Leptinus

testaceus_ (Fig. 103) is a British Insect, and besides occurring in Europe

is well known in North America. In Europe it has been found {221}in curious

places, including the nests of mice and bumble-bees. In America it has been

found on the mice themselves by Dr. Ryder, and by Riley in the nests of a

common field-mouse, together with its larva, which, however, has not been

described. The allied genus _Leptinillus_ is said by Riley to live on the

beaver, in company with _Platypsyllus_.[100] It has been suggested that the

natural home of the _Leptinus_ is the bee's nest, and that perhaps the

beetle merely makes use of the mouse as a means of getting from one nest of

a bumble-bee to another.

FAM. 15. SILPHIDAE.—_The mentum is usually a transverse plate, having in

front a membranous hypoglottis, which bears the exposed labial palpi, and

immediately behind them the so-called bilobed ligula. The anterior coxae

are conical and contiguous: prothoracic epimera and episterna not distinct.

Visible abdominal segments usually five, but sometimes only four, or as

many as seven. Tarsi frequently five-jointed, but often with one joint

less. Elytra usually covering the body and free at the tips, but

occasionally shorter than the body, and even truncate behind so as to

expose from one to four of the dorsal plates; but there are at least three

dorsal plates in a membranous condition at the base of the abdomen._ These

beetles are extremely diverse in size and form, some being very minute,

others upwards of an inch long, and there is also considerable range of

structure. In this family are included the burying-beetles (_Necrophorus_),

so well known from their habit of making excavations under the corpses of

small Vertebrates, so as to bury them. Besides these and _Silpha_, the

roving carrion-beetles, the family includes many other very different

forms, amongst them being the larger part of the cave-beetles of Europe and

North America. These belong mostly to the genera _Bathyscia_ in Europe, and

_Adelops_ in North America; but of late years quite a crowd of these

eyeless cave-beetles of the group Leptoderini have been discovered, so that

the European catalogue now includes about 20 genera and 150 species. The

species of the genus _Catopomorphus_ are found in the nests of ants of the

genus _Aphaenogaster_ in the Mediterranean region. Scarcely anything is

known as to the lives of either the cave-Silphidae or the myrmecophilous

forms.

The larvae of several of the larger forms of Silphidae are well known, but

very little has been ascertained as to the smaller forms. {222}Those of the

burying-beetles have spiny plates on the back of the body, and do not

resemble the other known forms of the family. The rule is that the three

thoracic segments are well developed, and that ten abdominal segments are

also distinct; the ninth abdominal segment bears a pair of cerci, which are

sometimes elongate. Often the dorsal plates are harder and better developed

than is usual in Coleopterous larvae. This is especially the case with some

that are endowed with great powers of locomotion, such as _S. obscura_

(Fig. 104). The food of the larvae is as a rule decomposing animal or

vegetable matter, but some are predaceous, and attack living objects. The

larger _Silpha_ larvae live, like the _Necrophorus_, on decomposing animal

matter, but run about to seek it; hence many specimens of some of these

large larvae may sometimes be found amongst the bones of a very small dead

bird. We have found the larva and imago of _S. thoracica_ in birds' nests

containing dead nestlings. _S. atrata_ and _S. laevigata_ make war on

snails. _S. lapponica_ enters the houses in Lapland and ravages the stores

of animal provisions. _S. opaca_ departs in a very decided manner from the

habits of its congeners, as it attacks beetroot and other similar crops in

the growing state; it is sometimes the cause of serious loss to the growers

of beet. The larvae of the group Anisotomides are believed to be chiefly

subterranean in habits; that of _A. cinnamomea_ feeds on the truffle, and

the beetle is known as the truffle-beetle.

[Illustration: Fig. 104—A, Larva of _Silpha obscura_. Europe. (After

Schiödte). B, _Ptomaphila lacrymosa_, Australia.]

The number of species of Silphidae known must be at present nearer 900 than

800. Of these an unusually large proportion belong to the European and

North American regions; Silphidae being apparently far from numerous in the

tropics. Rather more than 100 species are natives of Britain. The family

reappears in considerable force in New Zealand, and is probably well

represented {223}in South Australia and Tasmania. The most remarkable form

known is perhaps the Australian genus _Ptomaphila_ (Fig. 104, B). The

classification of the family is due to Dr. Horn.[101] The only change of

importance that has since been suggested is the removal of _Sphaerites_

from this family to Synteliidae. Anisotomidae and Clambidae have been

considered distinct families, but are now included in Silphidae.

FAM. 16. SCYDMAENIDAE.—_Minute Insects allied to Silphidae, but with the

hind coxae separated, and the facets of the eyes coarser; the tarsi are

five-jointed; the number of visible abdominal segments is six._ These small

beetles are widely spread over the earth's surface, and about 700 species

are now known, of which we have about a score in Britain; many live in

ants' nests, but probably usually rather as intruders than as guests that

have friendly relations with their hosts. Nothing is known as to their

life-histories, but the food of the imago, so far as is known, consists of

Acari. _Mastigus_ is a very aberrant form, found in moss and dead leaves in

Southern Europe. By means of _Brathinus_ the family is brought very near to

Silphidae; Casey, however, considers _Brathinus_ to belong to Staphylinidae

rather than to Scydmaenidae. The South European _Leptomastax_ is remarkable

on account of the slender, long, sickle-shaped mandibles. The Oriental

genus _Clidicus_ is the largest and most remarkable form of the family; it

has a very slender neck to its broad head, and is more than a quarter of an

inch long.

FAM. 17. GNOSTIDAE.—_Minute Insects with three-jointed antennae,

five-jointed tarsi, and three apparent ventral segments, the first of

which, however, is elongate, and consists of three united plates. Elytra

entirely covering the after-body._ The family consists of two species which

have been found in the nests of ants, of the genus _Cremastogaster_, in

Brazil.[102]

FAM. 18. PSELAPHIDAE.—_Very small Insects; the elytra much abbreviated,

usually leaving as much as half the abdomen uncovered; the maxillary palpi

usually greatly developed, and of a variety of remarkable forms; the

segments of the abdomen not more than seven in number, with little or no

power of movement. Tarsi with not more than three joints._ These small

Coleoptera mostly live in the nests of ants, and present a great diversity

of extraordinary {224}shapes, and very peculiar structures of the antennae

and maxillary palpi. Owing to the consolidation of some of its segments,

the abdomen frequently appears to have less than the usual number. In the

curious sub-family Clavigerides, the antennae may have the joints reduced

to two or even, to all appearance, to one; the tarsi suffer a similar

reduction. There are about 2500 species of Pselaphidae known; many of them

have never been found outside the ants' nests; very little, however, is

known as to their natural history. It is certain that some of them excrete,

from little tufts of peculiar pubescence, a substance that the ants are

fond of. The secretory patches are found on very different parts of the

body and appendages. _Claviger testaceus_ is fed by the ants in the same

way as these social Insects feed one another; the _Claviger_ has also been

seen to eat the larvae of the ants. They ride about on the backs of the

ants when so inclined. The family is allied to Staphylinidae, but is easily

distinguished by the rigid abdomen. Only one larva—that of _Chennium

bituberculatum_—is known. It appears to be very similar to the larvae of

Staphylinidae. The best account of classification and structure is that

given by M. Achille Raffray,[103] who has himself discovered and described

a large part of the known species.

FAM. 19. STAPHYLINIDAE.—_Elytra very short, leaving always some of the

abdominal segments exposed, and covering usually only two of the segments.

Abdomen usually elongate, with ten dorsal, and seven or eight ventral

segments; of the latter six or seven are usually exposed; the dorsal plates

as hard as the ventral, except sometimes in the case of the first two

segments; the segments very mobile, so that the abdomen can be curled

upwards. The number of tarsal joints very variable, often five, but

frequently as few as three, and not always the same on all the feet._

Staphylinidae (formerly called Brachelytra or Microptera) is one of the

most extensive of even the great families of Coleoptera; notwithstanding

their diversity, they may in nearly all cases be recognised by the more

than usually mobile and uncovered abdomen, combined with the fact that the

parts of the mouth are of the kind we have mentioned in Silphidae. The

present state of the classification of this family has been recently

discussed by Ganglbauer.[104]

{225}[Illustration: Fig. 105—Staphylinidae. A, Larva of _Philonthus

nitidus_. Britain. (After Schiödte.) B, _Ocypus olens_, Britain; C, tip of

abdomen, of _O. olens_ with stink-vessels.]

At present about 9000 species are known, some of which are minute, while

scarcely any attain a size of more than an inch in length, our common

British black cock-tail, or "devil's coach-horse beetle," _Ocypus olens_,

being amongst the largest. Though the elytra are short, the wings in many

forms are as large as those of the majority of beetles; indeed many

Staphylinidae are more apt at taking flight than is usual with Coleoptera;

the wings when not in use are packed away under the short elytra, being

transversely folded, and otherwise crumpled, in a complicated but orderly

manner. It is thought that the power of curling up the abdomen is connected

with the packing away of the wings after flight; but this is not the case:

for though the Insect sometimes experiences a difficulty in folding the

wings under the elytra after they have been expanded, yet it overcomes this

difficulty by slight movements of the base of the abdomen, rather than by

touching the wings with the tip. What the value of this exceptional

condition of short elytra and corneous dorsal abdominal segments to the

Insect may be is at present quite mysterious. The habits of the members of

the family are very varied; many run with great activity; the food is very

often small Insects, living or dead; a great many are found in fungi of

various kinds, and perhaps eat them. It is in this family that we meet with

some of the most remarkable cases of symbiosis, i.e. lives of two kinds of

creatures mutually accommodated with good will. The relations between the

Staphylinidae of the genera _Atemeles_ and _Lomechusa_, and certain ants,

in the habitations of which they dwell, are very interesting. The beetles

are never found out of the ants' nests, or at any rate not very far from

them. The most friendly relations exist between them and the ants: they

have patches of yellow hairs, and these {226}apparently secrete some

substance with a flavour agreeable to the ants, which lick the beetles from

time to time. On the other hand, the ants feed the beetles; this they do by

regurgitating food, at the request of the beetle, on to their lower lip,

from which it is then taken by the beetle (Fig. 82). The beetles in many of

their movements exactly resemble the ants, and their mode of requesting

food, by stroking the ants in certain ways, is quite ant-like. So

reciprocal is the friendship that if an ant is in want of food, the

_Lomechusa_ will in its turn disgorge for the benefit of its host. The

young of the beetles are reared in the nests by the ants, who attend to

them as carefully as they do to their own young. The beetles have a great

fondness for the ants, and prefer to sit amongst a crowd thereof; they are

fond of the ants' larvae as food, and indeed eat them to a very large

extent, even when their own young are receiving food from the ants. The

larva of _Lomechusa_, as described by Wasmann (to whom we are indebted for

most of our knowledge of this subject),[105] when not fully grown, is very

similar to the larvae of the ants; although it possesses legs it scarcely

uses them: its development takes place with extraordinary rapidity, two

days, at most, being occupied in the egg, and the larva completing its

growth in fourteen days. Wasmann seems to be of opinion that the ants

scarcely distinguish between the beetle-larvae and their own young; one

unfortunate result for the beetle follows from this, viz. that in the pupal

state the treatment that is suitable for the ant-larvae does not agree with

the beetle-larvae: the ants are in the habit of digging up their own kind

and lifting them out and cleaning them during their metamorphosis; they

also do this with the beetle-larvae, with fatal results; so that only those

that have the good fortune to be forgotten by the ants complete their

development. Thus from thirty _Lomechusa_ larvae Wasmann obtained a single

imago, and from fifty _Atemeles_ larvae not even one.

Many other Staphylinidae are exclusively attached to ants' nests, but most

of them are either robbers, at warfare with the ants—as is the case with

many species of _Myrmedonia_ that lurk about the outskirts of the nests—or

are merely tolerated by the ants, not receiving any direct support from

them. The most {227}remarkable Staphylinidae yet discovered are some

viviparous species, forming the genera _Corotoca_ and _Spirachtha_, that

have very swollen abdomens, and live in the nests of Termites in

Brazil:[106] very little is, however, known about them. A very large and

powerful Staphylinid, _Velleius dilatatus_, lives only in the nests of

hornets and wasps. It has been supposed to be a defender of the

Hymenoptera, but the recent observations of Janet and Wasmann make it clear

that this is not the case: the _Velleius_ has the power of making itself

disagreeable to the hornets by some odour, and they do not seriously attack

it. The _Velleius_ finds its nutriment in larvae or pupae of the wasps that

have fallen from their cells, or in other organic refuse.

The larvae of Staphylinidae are very similar to those of Carabidae, but

their legs are less perfect, and are terminated only by a single claw;

there is no distinct labrum. The pupae of some are obtected, _i.e._ covered

by a secondary exudation that glues all the appendages together, and forms

a hard coat, as in Lepidoptera. We have about 800 species of Staphylinidae

in Britain, and it is probable that the family will prove one of the most

extensive of the Order. It is probable that one hundred thousand species or

even more are at present in existence.

FAM. 20. SPHAERIIDAE.—_Very minute. Antennae eleven-jointed, clubbed. Tarsi

three-jointed. Abdomen with only three visible ventral segments_. This

family includes only three or four species of Insects about 1/50 of an inch

long. They are very convex, and be found walking on mud. _S. acaroides_

occurs in our fens. Mr. Matthews considers that they are most nearly allied

to Hydrophilidae.[107]

[Illustration: Fig. 106—_Trichopteryx fascicularis_. Britain. A, Outline of

perfect Insect; B, part of upper surface; C, larva from side; D, from

above; E, pupa; F, wing; G, natural size of imago.]

FAM. 21. TRICHOPTERYGIDAE.—_Extremely minute: antennae {228}clavicorn

(basal and apical joints thicker than middle joints); tarsi three-jointed;

elytra sometimes covering abdomen, in other cases leaving a variable number

of segments exposed; wings fringed._ This family comprises the smallest

Insects; _Nanosella fungi_ being only 1/100 of an inch long, while the

largest Trichopterygid is only 1/12 of an inch. The small size is not

accompanied by any degeneration of structure, the minute, almost invisible

forms, having as much anatomical complexity as the largest Insects. Very

little is known as to the natural history. Probably these Insects exist in

all parts of the world, for we have about eighty species in England, and

Trichopterygidae are apparently numerous in the tropics.[108]

FAM. 22. HYDROSCAPHIDAE.—_Extremely minute aquatic Insects, with elongate

abdomen. Antennae eight-jointed._ The other characters are much the same as

those we have mentioned for Trichopterygidae. The family is not likely to

come before the student, as only three or four species from Southern Europe

and North America are known.[109]

[Illustration: Fig. 107—A, Larva of _Orthoperus brunnipes_ (after Perris);

B, _O. atomarius_, perfect Insect. Britain.]

FAM. 23. CORYLOPHIDAE.—_Minute beetles. Tarsi four-jointed, but appearing

only three-jointed, owing to the hind joint being concealed by the

emarginate (or notched) second joint. Six free ventral segments. Maxillae

with only one lobe. Antennae of peculiar form._ There are about 200 species

of these little Insects, but the family is apparently represented all over

the world, and will probably prove to be much more extensive. The peculiar

larva of _Orthoperus brunnipes_ was found abundantly by Perris in thatch in

France. Mr. Matthews proposes to separate the genus _Aphanocephalus_ as a

distinct family, Pseudocorylophidae.[110] In Corylophidae the wings are

fringed with long hairs, as is the case in so many small Insects: the

species of _Aphanocephalus_ are rather larger Insects, and the wings are

not fringed; the tarsi are only three-jointed.

{229}FAM. 24. SCAPHIDIIDAE.—_Front coxae small, conical; prothorax very

closely applied to the after-body; hind coxae transverse, widely separated:

abdomen with six or seven visible ventral plates; antennae at the extremity

with about five joints that become gradually broader. Tarsi five-jointed._

This family consists of a few beetles that live in fungi, and run with

extreme rapidity; they are all small, and usually rare in collections. Some

of the exotic forms are remarkable for the extreme tenuity and fragility of

the long antennae, which bear fine hairs. The number of described species

does not at present reach 200, but the family is very widely distributed.

We have three or four species in Britain. All we know of the larvae is a

description of that of _Scaphisoma agaricinum_ by Perris;[111] it is like

the larva of Staphylinidae, there are nine abdominal segments in addition

to a very short, broad pseudopod, and very short cerci. This larva feeds on

agarics; it goes through its development in about three weeks; unlike the

adult it is not very active.

[Illustration: Fig. 108—_Scaphisoma agaricinum._ Britain. A Larva (after

Perris); B perfect Insect.]

FAM. 25. SYNTELIIDAE.—_Antennae clavicorn, with very large club: labium,

with hypoglottis and the parts beyond it, exposed. Front coxae transverse.

Abdomen with five visible ventral segments, and eight or nine dorsal, the

basal four of which are semi-corneous._ This family includes only five

species; its classification has given rise to much difference of opinion.

We have, after consideration of all its characters, established it as a

distinct family[112] allied to Silphidae. The perfect Insects live on the

sap running from trees: but nothing else is known of their natural history.

Like so many others of the very small families of aberrant Coleoptera, it

has a very wide distribution; _Syntelia_ being found in Eastern Asia and

Mexico, while the sub-family Sphaeritides occurs, as a single species, in

Europe and North America. The earlier instars are unknown.

[Illustration: Fig. 109—_Syntelia westwoodi._ Mexico. (From _Biol. Centr.

Amer._)]

{230}[Illustration: Fig. 110—_Platysoma depressum._ Europe. A, Larva (after

Schiödte); B, perfect Insect.]

FAM. 26. HISTERIDAE.—_Very compact beetles, with very hard integument,

short, bent antennae, with a very compact club: no hypoglottis. Elytra

closely applied to body, but straight behind, leaving two segments exposed.

Abdomen with five visible ventral segments; with seven dorsal segments, all

hard. Front coxae strongly transverse, hind coxae widely separated._ The

extremely compact form, and hard integument, combined with the peculiar

antennae—consisting of a long basal joint, six or seven small joints, and

then a very solid club of three joints covered with minute

pubescence—render these Insects unmistakable. The colour is usually shining

black, but there are numerous departures from this. The way in which these

Insects are put together so as to leave no chink in their hard exterior

armour when in repose, is very remarkable. The mouth-parts are rather

highly developed, and the family is entitled to a high rank; it consists at

present of about 2000 species;[113] in Britain we have about 40. The larvae

are without ocelli or labrum, but have well-developed mandibles, the second

and third thoracic segments being short, the ninth segment of the abdomen

terminal, with two distinctly jointed cerci.[114] Histeridae are common in

dung, in carcases, decaying fungi, etc., and some live under bark—these

being, in the case of the genus _Hololepta_, very flat. Some are small

cylinders, elaborately constructed, for entering the burrows of Insects in

wood (_Trypanaeus_); a certain number are peculiar to ants' nests. Formerly

it was supposed that the Insects were nourished on the decaying substances,

but it is now believed, with good reason, that they are eminently

predaceous, in both larval and imaginal {231}instars, and devour the larvae

of Diptera, etc. The relations of the ants'-nest forms to the ants is not

made out, but it is highly probable that they eat the ants' larvae, and

furnish the ants with some dainty relish. A few species live in company

with Termites.

FAM. 27. PHALACRIDAE.—_Body very compact; elytra entirely covering it;

apical joints of antennae rather broader, usually long; front coxae

globular; posterior coxae contiguous; abdomen with five visible ventral

segments; tarsi five-jointed, fourth joint usually small and obscure._ This

family consists entirely of small Insects: the tarsal structure is very

aberrant, and is also diverse, so that the student may without careful

observation pass the Insects over as having only four-jointed tarsi; their

structure, so far as the front two pairs are concerned, being very nearly

that of many Phytophaga. The larvae live in the heads of flowers,

especially of the flowers of Compositae. Having bored their way down the

stems, they pupate in earthen cocoons. Heeger[115] says that he has

observed in favourable seasons six generations; but the larvae die readily

in unfavourable seasons, and are destroyed in vast numbers when the meadows

are mowed. Seven years ago very little was known as to the family, and the

list of their species scarcely amounted to 100, but now probably 300 are

described. They occur in all parts of the world; we have fourteen in

Britain.

[Illustration: Fig. 111—_Olibrus bicolor._ Europe. A, Larva (after Heeger);

B, perfect Insect.]

FAM. 28. NITIDULIDAE.—_Antennae with a three-jointed club; all the coxae

separated, and each with an external prolongation; tarsi five-jointed, the

fourth joint smaller than any of the others; abdomen with five visible

plates._ These Insects are numerous, about 1600 species being at present

known; in many of them the elytra nearly or quite cover the hind body, but

in many others they are more or less abbreviated; in this case the Insects

may be distinguished from Staphylinidae by the form of their antennae, and

the smaller number of visible ventral segments. The habits are very varied,

a great many are found on flowers, others are attracted by the sap of

trees; some live in carcases. We have about 90 species in Britain; several

forms of {232}the genera _Meligethes_ and _Epuraea_ are among the most

abundant of our beetles. Most of what is known as to the larvae is due to

Perris; several have been found living in flowers; that of _Pria_ haunts

the flower of _Solanum dulcamara_ at the junction of the stamens with the

corolla; the larva of _Meligethes aeneus_ sometimes occasions much loss by

preventing the formation of seed in cultivated Cruciferae, such as Rape.

These floricolous larvae grow with great rapidity, and then leave the

flowers to pupate in the ground. The larva of _Nitidula_ lives in carcases,

though it is not very different from that of _Pria_. The larva of _Soronia_

lives in fermenting sap, and has four hooks curving upwards at the

extremity of the body. The curious genus _Cybocephalus_ consists of some

very small, extremely convex Insects that live in flowers in Southern

Europe; they have only four joints to the tarsi. The perfect Insects of the

group Ipides are remarkable from having a stridulating organ on the front

of the head. The classification of the well-known genus _Rhizophagus_ has

given rise to much discussion; although now usually placed in Nitidulidae,

we think it undoubtedly belongs to Cucujidae.

[Illustration: Fig. 112—_Pria dulcamarae._ Britain. A, Larva (after

Perris); B, perfect Insect.]

[Illustration: Fig. 113—_Temnochila coerulea._ Europe. A, Larva (after

Perris); B, perfect Insect.]

FAM. 29. TROGOSITIDAE.—_Differs from Nitidulidae in the structure of the

tarsi; these appear to be four-jointed, with the third joint similar in

size and form to the preceding; they are, however, really five-jointed, an

extremely short basal joint being present. Hind coxae contiguous. The club

of each antenna is bilaterally asymmetric, and the sensitive surface is

confined to certain parts of the joints._ There are some 400 or 500 species

of Trogositidae, but nearly all of them are exotic. The larvae (Fig. 113,

A), are predaceous, destroying other larvae in large numbers, and it is

probable that the imagos do the same. The larva of _Tenebroides_ (better

known as _Trogosita_) _mauritanica_ is found in corn and flour, and is said

to have sometimes been very {233}injurious by eating the embryo of the

corn, but it is ascertained that it also devours certain other larvae that

live on the corn. This beetle has been carried about by commerce, and is

now nearly cosmopolitan. Our three British species of Trogositidae

represent the three chief divisions of the family, viz. Nemosomides,

Temnochilides, Peltides; they are very dissimilar in form, the Peltides

being oval, with retracted head. It is doubtful whether the members of the

latter group are carnivorous in any of their stages; it is more probable

that they live on the fungi they frequent. Peltidae stand as a distinct

family in many works.[116]

[Illustration: Fig. 114—_Bitoma crenata._ Britain. A, Larva (after Perris);

B, perfect Insect.]

FAM. 30. COLYDIIDAE.—_Antennae with a terminal club, tarsi four-jointed,

none of the joints broad; front and middle coxae small, globose, embedded;

hind coxae transverse, either contiguous or separated; five visible ventral

segments, several of which have no movement._ This is a family of interest,

owing to the great diversity of form, to the extraordinary sculpture and

clothing exhibited by many of its members, and to the fact that most of its

members are attached to the primitive forests, and disappear entirely when

these are destroyed. We have fifteen species in Britain, but about half of

them are of the greatest rarity. There are about 600 species known at

present; New Zealand has produced the greatest variety of forms; the

forests of Teneriffe are rich in the genus _Tarphius_. The sedentary lives

of many of these beetles are very remarkable; the creatures concealing

themselves in the crannies of fungus-covered wood, and scarcely ever

leaving their retreats, so that it is the rarest circumstance to find them

at any distance from their homes. _Langelandia anophthalma_ lives entirely

underground and is quite blind, the optic lobes being absent. Some

Colydiidae are more active, and enter the burrows of wood-boring Insects to

destroy the larvae (_Colydium_). Few of the larvae are known; but all

appear to have the body terminated by peculiar hard corneous processes, as

is the case with a great variety of Coleopterous larvae that live in

wood.[117]

{234}FAM. 31. RHYSODIDAE.—_Tarsi four-jointed; mouth-parts covered by the

large mentum; front tibiae notched on the inner edge._ This family consists

only of a few species, but is found nearly all over the world in the warm

and temperate regions. In many of their characters they resemble the

Adephaga, but are very different in appearance and in the mouth. The larvae

are not known. Some authorities think these Insects should be placed in the

series Adephaga,[118] but it is more probable that they will prove to be

amongst the numerous aberrant forms of Coleoptera that approach the various

large natural series, without really belonging to them. The three families,

Colydiidae, Cucujidae, and Rhysodidae, exhibit relations not only with

other families of the Coleoptera Polymorpha, but also with most of the

great series; Adephaga, Rhynchophora, Phytophaga, and Heteromera, being

each closely approached.

FAM. 32. CUCUJIDAE.—_Tarsi five- or four-jointed, the first joint often

short: antennae sometimes clubbed, but more often quite thin at the tip;

front and middle coxae deeply embedded, globular, but with an angular

prolongation externally; abdomen with five visible ventral segments, all

movable._ This family and the Cryptophagidae are amongst the most difficult

families to define; indeed it is in this portion of the Clavicorns that an

extended and thorough study is most urgently required. The Cucujidae

include a great diversity of forms; they are mostly found under the bark of

trees, and many of them are very flat. Many of the larvae are also very

flat, but Ferris says there is great diversity in their structure: they are

probably chiefly carnivorous. There are about 400 species described; we

have nearly a score in Britain.

[Illustration: Fig. 115—_Brontes planatus._ Britain. A, Larva; B, pupa; C,

perfect Insect. (A and B after Perris.)]

The family Cupesidae of certain taxonomists must be at present associated

with Cucujidae, though the first joint of the tarsus is elongate.

{235}FAM. 33. CRYPTOPHAGIDAE.—_Front and middle coxae very small and deeply

embedded; antennae with enlarged terminal joints; tarsi five-jointed, the

posterior sometimes in the male only four-jointed; abdomen with five

visible ventral segments, capable of movement, the first much longer than

any of the others._ A small family composed of obscure forms of minute

size, which apparently have mould-eating habits, though very little is

known on this point and several of the genera (_Antherophagus_,

_Telmatophilus_) are found chiefly on growing plants, especially in

flowers. Although the imago of _Antherophagus_ lives in flowers, yet the

larva has only been found in the nests of bumble-bees; there is reason for

believing that the imago makes use of the bee to transport it from the

flowers it haunts to the nests in which it is to breed;[119] this it does

by catching hold of the bee with its mandibles when the bee visits the

flower in which the beetle is concealed. It is strange the beetle should

adopt such a mode of getting to its future home, for it has ample wings. We

must presume that its senses and instinct permit it to recognise the bee,

but do not suffice to enable it to find the bee's nest. Some of the larvae

of the genus _Cryptophagus_ are found abundantly in the nests of various

wasps, where they are probably useful as scavengers, others occur in the

nests of social caterpillars, and they are sometimes common in loose straw;

this being the habitat in which Perris found the one we figure.

[Illustration: Fig. 116—_Cryptophagus dentatus._ Britain. A, Larva (after

Perris); B, perfect Insect.]

FAM. 34. HELOTIDAE.—_Front and middle coxal cavities round, with scarcely

any angular prolongation externally; all the coxae widely separated; five

visible ventral segments, all mobile._ The Insects of this family are

closely allied to Trogositidae and Nitidulidae, and have the tarsal

structure of the former family; but the Helotidae are different in

appearance from any members of either of these two families, and are

readily distinguished by the coxal character. They are frequently

classified with the Erotylidae, from which they differ by the differently

shaped feet, especially by the diminished basal joint. {236}There is but

one genus, and for a long time only two or three species were known, and

were great rarities in collections; in the last few years the number has

been raised to nearly forty.[120] They are remarkable beetles with oblong

form, and a somewhat metallic upper surface, which is much sculptured, and

possesses four yellow, smooth spots on the elytra. According to Mr. George

Lewis they are found feeding at the running sap of trees, but the larvae

are not known. Helotidae are peculiar to the Indo-Malayan region (including

Japan) with one species in Eastern Africa.

FAM. 35. THORICTIDAE.—_Tarsi five-jointed, none of the joints broad; front

coxae small, rather prominent, but not at all transverse; five visible

ventral plates, all mobile; metasternum very short; antennae short, with a

solid club._ This little family, consisting of the genus _Thorictus_,

appears to be a distinct one, though the structure has only been very

imperfectly studied. It is peculiar to the Mediterranean region, where the

species live in ants' nests. They appear to be on terms of great intimacy

with the ants; a favourite position of the beetle is on the scape of the

antenna of an ant; here it hooks itself on firmly, and is carried about by

the ant. Like so many other ants'-nest beetles, Thorictidae possess tufts

of golden hair, which secrete some substance, the flavour of which is

appreciated by the ants; these tufts in Thorictidae are situated either at

the hind angles of the pronotum, or on the under surface of the body on

each side of the breast; Wasmann thinks that when the beetles are riding

about, as above described, the ants have then an opportunity of getting at

the patches on the under surface.

[Illustration: Fig. 117—_Tritoma bipustulata._ Erotylidae. Britain. A,

Larva (after Perris); B, perfect Insect.]

FAM. 36. EROTYLIDAE.—_Tarsi five-jointed, but with the fourth usually very

small, the first three more or less broad and pubescent beneath. Antennae

strongly clubbed. Front and middle coxal acetabula round, without angular

prolongation externally; five visible ventral segments._ This is now a

large and important family of about 1800 species, but it is chiefly exotic

and tropical, its members haunting the fungoid growths {237}in forests. We

have only six species in Britain, and the whole of Europe has only about

two dozen, most of them insignificant (and in the case of the Dacnides

aberrant, approaching the Cryptophagidae very closely). The sub-family

Languriides (quite wanting in Europe) consists of more elongate Insects,

with front acetabula open behind; they have different habits from

Erotylides proper; some are known to live as larvae in the stems of

herbaceous plants. They possess a highly developed stridulating organ on

the front of the head. The Clavicorn Polymorpha are very closely connected

with the Phytophaga by Languriides.

FAM. 37. MYCETOPHAGIDAE.—_Tarsi four-jointed, slender, the front feet of

the male only three-jointed; coxae oval, not deeply embedded; abdomen with

five ventral segments, all movable._ A small family, of interest chiefly

because of the anomaly in the feet of the two sexes, for which it is

impossible to assign any reason. The species are small, uninteresting

Insects that live chiefly on Cryptogams of various kinds, especially in

connection with timber; the larvae being also found there. There are about

a dozen species in Britain, and scarcely 100 are described from all the

world. The Diphyllides, placed by Leconte and Horn in this family, seem to

go better in Cryptophagidae.

[Illustration: Fig. 118—_Litargus bifasciatus._ Mycetophagidae. Britain. A,

Larva (after Perris); B, perfect Insect.]

FAM. 38. COCCINELLIDAE (_Lady-birds_).—_Tarsi apparently three-jointed; the

first two joints pubescent beneath; the third joint consisting really of

two joints, the small true third joint being inserted near the base of the

second joint, the upper surface of which is grooved to receive it. Head

much concealed by the thorax. Antennae feebly clubbed._ The lady-birds

number fully 2000 species. The structure of their feet distinguishes them

from nearly all other Coleoptera except Endomychidae, which are much less

rotund in form, and have larger antennae. One genus of

Endomychids—_Panomoea_—bears, however, a singular resemblance to

lady-birds, both in form and style of coloration. Several species of

Coccinellidae are remarkable on account of the numerous variations in

colour they present. Coccinellidae frequently multiply to an enormous

extent, and are of great value, as they destroy wholesale the plant-lice,

scale-Insects, {238}and Acari that are so injurious to cultivated plants.

They also eat various other soft-bodied Insects that attack plants. As they

are excessively voracious, and are themselves singularly free from enemies

and multiply with great rapidity, all these features of their economy

render them of inestimable value to the agriculturist and horticulturist.

The species of the sub-family Epilachnides feed on plants, and one or two

are occasionally injurious. The body-fluid of Coccinellidae has an

unpleasant odour and taste. Many lady-birds have the power of exuding, when

disturbed, small quantities of a yellow fluid. Lutz has shown that this is

not a special secretion, but an exudation of the fluid of the body that

takes place through a small orifice at the tip of the tibia, from pressure

caused by contraction of the body and limb.[121]

The larvae are much more active than beetle-larvae usually are, and many of

them are very conspicuous when running about on plants to hunt their prey.

They usually cast their skins three times, and sometimes concomitantly

change a good deal in colour and form; the larval life does not usually

exceed four or five weeks; at the end of which time the larva suspends

itself by the posterior extremity, which is glued by a secretion to some

object; the larval skin is pushed back to the anal extremity, disclosing

the pupa; this differs in several respects from the usual pupa of beetles;

it is harder, and is coloured, frequently conspicuously spotted, and

dehisces to allow the escape of the beetle, so that the metamorphosis is

altogether more like that of Lepidoptera than that of Coleoptera. There is

much variety in the larvae; some of them bear large, complexly-spined,

projections; those of the group Scymnites have small depressions on the

surface, from which it has been ascertained that waxy secretions exude; but

in _Scymnus minimus_ no such excretions are formed. Certain species, when

pupating, do not shuffle the skin to the extremity of the body, but retain

it as a covering for the pupa. The larvae that feed on plants are much less

active than the predaceous forms. We are well supplied with Coccinellidae

in Britain, forty species being known here.

The systematic position of Coccinellidae amongst the Coleoptera has been

for long a moot point. Formerly they were associated with various other

beetles having three-jointed, or apparently three-jointed, feet, as a

series with the name Trimera, or {239}Pseudotrimera. But they are generally

placed in the Clavicorn series, near Endomychidae. Verhoeff has recently

made considerable morphological studies on the male genital organs of

Coleoptera, and as the result, he concludes that Coccinellidae differ

radically from all other Coleoptera as regards these structures, and he

therefore treats them as a distinct series or sub-order, termed

Siphonophora. The genus _Lithophilus_ has been considered doubtfully a

member of Coccinellidae, as the tarsi possess only in a slight degree the

shape characteristic of the family: Verhoeff finds that they are truly

Coccinellidae, forming a distinct division, Lithophilini; and our little

species of _Coccidula_, which have somewhat the same appearance as

Lithophilini, he treats as another separate group, Coccidulini.

FAM. 39. ENDOMYCHIDAE.[122]—_Tarsi apparently three-jointed, the first two

joints broad, the terminal joint elongate; at the base of the terminal

joint there is, however, a very small joint, so that the tarsi are

pseudotetramerous; antennae rather large, with a large club; labium not at

all retracted behind the mentum; front and middle coxae globose; abdomen

with five movable ventral segments, and a sixth more or less visible at the

tip._ This family includes a considerable diversity of elegant Insects that

frequent fungoid growths on wood. It comprises at present fully 500

species, but nearly the whole of them are exotic, and inhabit the tropical

forests. We have only two British species, both of which are now rarities,

but apparently were much commoner at the beginning of the century. The

larvae are broader than is usual in Coleoptera; very few, however, are

known.

[Illustration: Fig. 119—_Mycetaea hirta._ Britain. A, Larva (after

Blisson); B, perfect Insect.]

FAM. 40. MYCETAEIDAE.—_Tarsi four-jointed, the first two joints not very

different from the third, usually slender; abdomen with five visible

ventral segments, which are movable; front and middle coxae globular._ The

little Insects composing this family are by many placed as a division of

Endomychidae, and Verhoeff is of opinion that the group is an altogether

artificial one; but we think, with Duval, it makes matters simpler to

separate them. There are only {240}some forty or fifty species, found

chiefly in Europe and North America. We have three in Britain; one of

these, _Mycetaca hirta_ is very common, and may be found in abundance in

cellars in the heart of London, as well as elsewhere; it is said to have

injured the corks of wine-bottles, and to have caused leakage of the wine,

but we think that it perhaps only increases some previous deficiency in the

corkage, for its natural food is fungoid matters. The larva is remarkable

on account of the clubbed hairs at the sides of the body.

FAM. 41. LATRIDIIDAE.—_Tarsi three-jointed; anterior coxal cavities round,

not prolonged externally; abdomen with five visible and mobile ventral

segments._ Very small Insects, species of which are numerous in most parts

of the world, the individuals being sometimes very abundant. The larvae

(Fig. 120, A) are said by Perris to have the mandibles replaced by fleshy

appendages. The pupa of _Latridius_ is remarkable, on account of the

numerous long hairs with heads instead of points; the larva of _Corticaria_

is very like that of _Latridius_, but some of the hairs are replaced by

obconical projections. The sub-family Monotomides is by many treated as a

distinct family; they have the elytra truncate behind, exposing the

pygidium, and the coxae are very small and very deeply embedded. Most of

the Latridiidae are believed to live on fungoid matters; species of

_Monotoma_ live in ants' nests, but probably have no relations with the

ants. A few species of Latridiides proper also maintain a similar life;

_Coluocera formicaria_ is said to be fond of the stores laid up by

_Aphaenogaster structor_ in its nests. About 700 species are now known;

scarcely any of the individuals are more than one-tenth of an inch long. We

have about 40 species in Britain. The North American genus _Stephostethus_

has the prosternum constructed behind the coxae, somewhat in the same

manner as it is in the Rhynchophorous series of Coleoptera.

[Illustration: Fig. 120—_Latridius minutus._ Britain. A, Larva (after

Perris); B, perfect Insect.]

FAM. 42. ADIMERIDAE.—_Tarsi appearing only two-jointed, a broad basal joint

and an elongate claw-bearing joint, but between the two there are two very

small joints._ This family consists only of the American genus _Adimerus_;

nothing is known of {241}the life-history of these small Insects. They are

of some interest, as this structure of the foot is not found in any other

beetles.

[Illustration: Fig. 121—_Adimerus setosus._ Adimeridae. A, the Insect; B,

one foot more enlarged. Mexico. From _Biol. Centr. Amer. Col._ ii. pt. i.]

[Illustration: Fig. 122—_Tiresias serra._ Larva. New Forest.]

FAM. 43. DERMESTIDAE.—_Tarsi five-jointed; antennae usually short, with the

club frequently very large in proportion, and with the under side of the

thorax bearing a hollow for its reception. Front coxae rather long,

oblique: hind coxa formed to receive the femur when in repose._ A family of

300 or 400 species of small or moderate-sized beetles; the surface, usually

covered with fine hair, forming a pattern, or with scales. _Byturus_, the

position of which has long been disputed, has now been placed in this

family; it has a more imperfectly formed prosternum, and the third and

fourth joints of the tarsi are prolonged as membranous lobes beneath; the

hind coxae leave the femora quite free. Dermestidae in the larval state

nearly all live on dried animal matter, and are sometimes very destructive;

some of them totally destroy zoological collections. They are very

remarkable on account of the complex clothing of hairs they bear; they have

good powers of locomotion, and many of them have a peculiar gait, running

for a short distance, then stopping and vibrating some of their hairs with

extreme rapidity. They exhibit great variety of form. Many of them are

capable of supporting life for long periods on little or no food, and in

such cases moult an increased number of times: pupation takes place in the

larval skin. _Anthrenus fasciatus_ has been reared in large numbers on a

diet of dried horse-hair in furniture. The young larva of this species

observed by the writer did not possess the remarkable, complex arrangement

of hairs that appeared when it was further grown. The most curious of

Dermestid larvae is that of _Tiresias serra_, which lives amongst cobwebs

in {242}old wood, and probably feeds on the remains of Insects therein,

perhaps not disdaining the cobwebs themselves. Attention has been

frequently called to the hairs of the larvae of these Insects, but they

have never been adequately discussed, and their function is quite unknown.

FAM. 44. BYRRHIDAE (_Pill-beetles_).—_Oval or round, convex beetles; tarsi

five-jointed, front coxae not exserted, transverse; hind coxa shielding the

retracted femur. The whole of the appendages capable of a complete

apposition to the body._ Although a small family of only 200 or 300

species, Byrrhidae are so heterogeneous that no characteristic definition

that will apply to all the sub-families can be framed. Very little is known

as to their life-histories. _Byrrhus pilula_ is one of our commonest

beetles, and may be found crawling on paths in early spring even in towns;

it moves very slowly, and when disturbed, at once contracts the limbs so

completely that it looks like an inanimate object. The larva is

cylindrical, soft; the prothoracic and last two abdominal segments are

larger than the others, the last bearing two pseudopods; its habits are

unknown, and no good figure exists of it.

The chief groups of Byrrhidae are Nosodendrides, Byrrhides (including

Amphicyrtides), Limnichides, and Chelonariides. The first consists of

species frequenting the exuding sap of trees; they have an unusually large

mentum, abruptly clubbed antennae, and the head cannot be retracted and

concealed. The genus _Nosodendron_ seems to be distributed over a large

part of the world. The Byrrhides have the antennae gradually thicker

towards the tip, the mentum small, and the head and thorax so formed that

the former can be perfectly retracted. The species are rather numerous, and

are found in the northern and antipodeal regions, being nearly completely

absent from the tropics. The Limnichides are minute Insects living in very

moist places; they have small delicate antennae, which are imperfectly

clubbed. The group is very widely distributed.

The Chelonariides are a very peculiar form of Coleoptera: oval Insects of

small size with the prothorax so formed that the head can be withdrawn

under (rather than into) it, and then abruptly inflexed, so that the face

then forms part of the under surface: the antennae have the basal three

joints thicker than the others; these being not in the least clubbed, but

having the {243}joints so delicately connected that the organs are rarely

unmutilated. The modifications of the head and prothorax are quite unlike

those of other Byrrhidae, and if the Chelonariides do not form a distinct

family, they should be associated with Dascillidae. Nothing is known as to

the earlier stages. They are chiefly tropical Insects, though one species

is found in North America.

FAM. 45. CYATHOCERIDAE.—_Minute Insects of broad form; parts of the mouth

concealed; antennae four-jointed; tarsi not divided into joints; prosternum

small._ The only species of this aberrant family, _Cyathocerus horni_, has

been found in Central America. Nothing is known as to its life-history.

FAM. 46. GEORYSSIDAE.—_Antennae short, clubbed; tarsi four-jointed;

prosternum very small; front coxae exserted, but not contiguous._ There are

about two dozen species of these small beetles known. Our British

_Georyssus pygmaeus_ lives in extremely wet places, and covers itself with

a coating of mud or fine sand so that it can only be detected when in

movement. Nothing further is known as to its life-history or habits.

Members of the genus have been detected in widely-separated parts of the

globe.

FAM. 47. HETEROCERIDAE.—_Labrum and mandibles projecting forwards; antennae

short, the terminal seven joints broad and short, forming a sort of broad

serrate club; legs armed with stout spines; tarsi four-jointed._ The

Heteroceridae are small beetles covered with very dense but minute

pubescence; they live in burrows among mud or sand in wet places, and are

found in many parts of the world. They possess a stridulating organ in the

form of a slightly elevated curved line on each side of the base of the

abdomen, rubbed by the posterior femur. The larvae live in the same places

as the beetles; they have well-developed thoracic legs, the mandibles are

porrect, the three thoracic segments rather large, and the body behind

these becomes gradually narrower; they are believed to eat the mud amongst

which they burrow. We have seven British species of Heteroceridae.

FAM. 48. PARNIDAE.—_Prosternum distinct in front of the coxae, usually

elongate, behind forming a process received into a definite cavity on the

mesosternum; head retractile, the mouth protected by the prosternum. Tarsi

five-jointed, terminal joint long._ {244}Although the characters of these

Insects are not very different from those of Byrrhidae, of Dascillidae, and

even of certain Elateridae, there is practically but little difficulty in

distinguishing Parnidae. They are of aquatic habits, though many, in the

perfect state, frequently desert the waters. There are about 300 or 400

species known, but the family is doubtless more extensive, as these small

beetles attract but little notice. There are two groups:—1. Parnides, in

which the front coxae have a considerable transverse extension, the

antennae are frequently short and of peculiar structure, and the body is

usually clothed with a peculiar, dense pubescence. 2. Elmides, with round

front coxae, a bare, or feebly pubescent body, and simple antennae.

_Parnus_ is a genus commonly met with in Europe, and is less aquatic in

habits than its congeners; it is said to enter the water carrying with it a

coating of air attached to its pubescence. Its larvae are not well known;

they live in damp earth near streams, and are said to much resemble the

larvae of Elateridae. _Potamophilus acuminatus_ has a very interesting

larva, described by Dufour; it lives on decaying wood in the Adour. It is

remarkable from the ocelli being arranged so as to form an almost true eye

on each side of the head; there are eight pairs of abdominal spiracles, and

also a pair on the mesothorax, though there are none on the pro- or

meta-thorax; each of the stigmata has four elongate sacs between it and the

main tracheal tube; the body is terminated by a process from which there

can be protruded bunches of filamentous branchiae. The larvae of

_Macronychus quadrituberculatus_ is somewhat similar, though the features

of its external structure are less remarkable. The Elmides live attached to

stones in streams; the larva is rather broad, fringed at the sides of the

body, and bears behind three elegant sets of fine filamentous branchiae.

The North American genus _Psephenus_ is placed in Parnidae, though instead

of five, the male has seven, the female six, visible ventral segments; the

larva is elliptical, with dilated margins to the body. Friederich, has

given,[123] without mentioning any names, a detailed account of Brazilian

Parnid larvae, that may perhaps be allied to _Psephenus_.

FAM. 49. DERODONTIDAE.—_Tarsi five-jointed, slender, fourth joint rather

small; front coxae prominent and transversely {245}prolonged; middle coxae

small; abdomen with five visible segments, all mobile, the first not

elongated._ One of the smallest and least known of the families of

Coleoptera; it consists of four or five species of small Insects of the

genera _Derodontus_ and _Peltasticta_, found in North America, Europe, and

Japan. The distinction of the family from Cleridae is by no means certain;

our European _Laricobius_ apparently possessing characters but little

different. Nothing is known as to the life-histories.

FAM. 50. CIOIDAE.—_Small or minute beetles; antennae short, terminal joints

thicker; tarsi short, four-jointed; anterior and middle coxae small, oval,

deeply embedded; abdomen with five ventral segments, all mobile._ The

position of these obscure little Insects seems to be near Colydiidae and

Cryptophagidae, though they are usually placed near Bostrichidae. So far as

known, they all live in fungi, or in wood penetrated by fungoid growths.

The cylindrical larvae live also in similar matter; they usually have the

body terminated behind by one or two hooks curved upwards; that of _Cis

melliei_ (Fig. 124) has, instead of these hooks, a curious chitinous tube.

About 300 species of the family are now known; a score, or so, occurring in

Britain. The Hawaiian Islands have a remarkably rich and varied fauna of

Cioidae.

[Illustration: Fig. 123—_Derodontus maculatus._ North America.]

[Illustration: Fig. 124—_Cis melliei._ Martinique. A, Perfect Insect; B,

pupa; C, larva; D, terminal portion of body of larva. (After Coquerel.)]

FAM. 51. SPHINDIDAE.—This family of half a dozen species of rare and small

Insects, differs from Cioidae by the tarsi being five-jointed at any rate

on the front and middle feet, opinions differing as to whether the number

of joints of the hind tarsi is four or five. These Insects live in fungi

growing in wood, _e.g._ _Reticularia hortensis_, that are at first pulpy

and {246}afterwards become powder. The larvae of both of our British

genera, _Sphindus_ and _Aspidiphorus_, have been described by Perris, who

considers them allied to the fungivorous Silphidae and Latridiidae. The

systematic position of these Insects has been the subject of doubt since

the days of Latreille.

FAM. 52. BOSTRICHIDAE (APATIDAE of some authors).—_Tarsi five-jointed, but

the first joint very short and imperfectly separated from the second; front

coxae prominent, contiguous, very little extended transversely; five

visible ventral segments._ The Bostrichidae attack dry wood, and sometimes

in such large numbers that timber is entirely destroyed by them; most of

them make cylindrical burrows into the wood. The larvae have the posterior

part of the body incurved, and resemble the wood-boring larvae of Anobiidae

rather than the predaceous larvae of Cleridae. We follow Leconte and Horn

in placing Lyctides as a division of Bostrichidae; although differing very

much in appearance, they have similar habits and larvae. The typical

Bostrichides are remarkable for their variety of sculpture and for the

shapes of the posterior part of the body; this part is more or less

conspicuously truncate, and furnished with small prominences. _Dinapate

wrightii_, found in the stems of a species of _Yucca_ in the Mojave desert

of California, attains a length of nearly two inches; its larva is

extremely similar to that of _A. capucina_. Some of the forms (_Phonapate_)

stridulate in a manner peculiar to themselves, by rubbing the front leg

against some projections at the hind angle of the prothorax. Upwards of 200

species of the family are known. In Britain we have only four small and

aberrant forms.

[Illustration: Fig. 125—_Apate capucina._ Europe. A, Larva (after Perris);

B, perfect Insect.]

FAM. 53. PTINIDAE.—_Tarsi five-jointed, first joint not reduced in size,

often longer than second; front and middle coxae small, not transversely

extended, the former slightly prominent; five visible ventral segments;

prosternum very short._ Here are included two sub-families, Ptinides and

Anobiides; they are considered as distinct families by many authors, but in

the present imperfect state of knowledge[124] it is not necessary to treat

them separately.

{247}[Illustration: Fig. 126—"Biscuit-weevil." _Anobium paniceum._]

[Illustration: Fig. 127.—Early stages of _Anobium paniceum_. A, Eggs,

variable in form; B, larva; C, pupa; D, asymmetrical processes terminating

body of pupa. [This larva is probably the "book-worm" of librarians].]

Ptinidae are sometimes very destructive to dried animal matter, and attack

specimens in museums; Anobiides bore into wood, and apparently emerge as

perfect Insects only for a very brief period; _Anobium_ (_Sitodrepa_)

_paniceum_ is, however, by no means restricted in its tastes; it must

possess extraordinary powers of digestion, as we have known it to pass

several consecutive generations on a diet of opium; it has also been

reported to thrive on tablets of dried compressed meat; in India it is said

to disintegrate books; a more usual food of the Insect is, however, hard

biscuits; weevilly biscuits are known to every sailor, and the so-called

"weevil" is usually the larva of _A. paniceum_ (Fig. 127, B). In the case

of this Insect we have not detected more than one spiracle (situate on the

first thoracic segment); the other known larvae of Anobiides are said to

possess eight abdominal spiracles. The skeleton in some of this sub-family

is extremely modified, so as to allow the Insects to pack themselves up in

repose; the head is folded in over the chest, and a cavity existing on the

breast is thus closed by the head; in this cavity the antennae and the

prominent mouth-parts are received and protected; the legs shut together

{248}in an equally perfect manner, so that no roughness or chink remains,

and the creature looks like a little hard seed. _Anobium striatum_ is a

common Insect in houses, and makes little round holes in furniture, which

is then said to be "worm-eaten." _A._ (_Xestobium_) _tessellatum_, a much

larger Insect, has proved very destructive to beams in churches, libraries,

etc. These species are the "death-watches" or "greater death-watches" that

have been associated with the most ridiculous superstitions (as we have

mentioned in Volume V., when speaking of the lesser death-watches, or

Psocidae). The ticking of these Insects is really connected with sex, and

is made by striking the head rapidly against the wood on which the Insect

is standing.

The very anomalous genus _Ectrephes_ (Fig. 128) is found in ants' nests in

Australia. Westwood placed it in Ptinidae. Wasmann has recently treated it

as a distinct family, Ectrephidae, associating it with _Polyplocotes_ and

_Diplocotes_, and treating them as allied to Scydmaenidae.

[Illustration: Fig. 128—_Ectrephes kingi._ West Australia. (After

Westwood.)]

FAM. 54. MALACODERMIDAE.—_Seven (or even eight) visible ventral segments,

the basal one not co-adapted in form with the coxae; tarsi five-jointed.

Integument softer than usual, the parts of the body not accurately

co-adapted._ This important family includes a variety of forms: viz.

Lycides, Drilides, Lampyrides, Telephorides; though they are very different

in appearance, classifiers have not yet agreed on separating them as

families. Of these the Lampyrides, or glow-worms, are of special interest,

as most of their members give off a phosphorescent light when alive; in

many of them the female is apterous and like a larva, and then the light it

gives is usually conspicuous, frequently much more so than that of its

mate; in other cases the males are the most brilliant. The exact importance

of these characters in the creatures' lives is not yet clear, but it

appears probable that in the first class of cases the light of the female

serves as an attraction to the male, while in the second class the very

brilliant lights of the male serve as an amusement, or as an incitement to

rivalry amongst the individuals of this sex.

{249}[Illustration: Fig. 129—_Phengodes hieronymi._ Cordoba, South America.

(After Haase.) A, Male; B, female. _l_, _l_, Positions of luminous spots;

_ls_, spiracles. About × 3.]

The well-known fire-flies (_Luciola_) of Southern Europe are an example of

the latter condition. They are gregarious, and on calm, warm nights crowds

of them may be seen moving and sparkling in a charming manner. These

individuals are all, or nearly all, males; so rare indeed is the female

that few entomologists have even noticed it. The writer once assisted in a

large gathering of _Luciola italica_ in the Val Anzasca, which consisted of

many hundreds of specimens; all of those he caught, either on the wing or

displaying their lights on the bushes, were males, but he found a solitary

female on the ground. This sex possesses ordinary, small eyes instead of

the large, convex organs of the male, and its antennae and legs are much

more feeble, so that though provided with elytra and wings it is altogether

a more imperfect creature. Emery has given an account of his observations

and experiments on this Insect, but they do not give any clear idea as to

the exact function of the light.[125] In our British glow-worm the female

is entirely apterous—hence the name glow-worm—but the male has elytra and

ample wings, and frequently flies at night into lighted apartments.

Although so little has been ascertained as to the light of Lampyridae,

there are two facts that justify us in supposing that it is in some way of

importance to the species. These are: (1) that in a great many species the

eyes have a magnificent and unusual development; (2) that the habits of the

creatures are in nearly all cases nocturnal. It is true that the little

_Phosphaenus hemipterus_ is said to be diurnal in habits, but it is

altogether an exceptional form, being destitute of wings in both sexes, and

possessed of only very feeble light-giving powers, and we have, moreover,

very little real knowledge as to its natural history; it is said {250}that

the female is of the utmost rarity, though the male is not uncommon.

The nature of the luminosity of _Lampyris_ has given rise to many

contradictory statements; the light looks somewhat like that given off by

phosphorus, and is frequently spoken of as phosphorescence; but

luminescence is a better term. The egg, larva, pupa, and male are luminous

as well as the female (at any rate in _L. noctiluca_); the luminescence is,

however, most marked in the female imago, in which it is concentrated near

the extremity of the abdomen; here there are two strata of cells, and many

fine capillary tracheae are scattered through the luminous substance.

Wielowiejski concludes that the light-producing power is inherent in the

cells of the luminous organ, and is produced by the slow oxidation of a

substance formed under the influence of the nervous system. The cells are

considered to be essentially similar to those of the fat-body.[126] The

luminescence of Lampyridae is very intermittent, that is to say, it is

subject to rapid diminutions and increases of its brilliancy; various

reasons have been assigned for this, but all are guesses, and all that can

be said is that the changes are possibly due to diminution or increase of

the air-supply in the luminous organ, but of the way in which this is

controlled there seems to be no evidence. Considerable difference of

opinion has existed as to the luminescence of the eggs of _Lampyris_. If it

exist in the matter contained in the egg, it is evident that it is

independent of the existence of tracheae or of a nervous system. Newport

and others believed that the light given by the egg depended merely on

matter on its exterior. The observations of Dubois[127] show, however, that

it exists in the matter in the egg; he has even found it in the interior of

eggs that had been deposited unfertilised.

From time to time, since the commencement of the nineteenth century, there

have appeared imperfect accounts of extraordinary light-giving larvae found

in South America, of various sizes, but attaining in some cases a length,

it is said, of three inches; they are reported as giving a strong red light

from the two extremities of the body, and a green light from numerous

points along the {251}sides of the body, and hence are called, it is said,

in Paraguay the railway-beetle. We may refer the reader to Haase's

paper[128] on the subject of these "larvae," as we can here only say that

it appears probable that most of these creatures may prove to be adult

females of the extraordinary group Phengodini, in which it would appear

that the imago of the female sex is in a more larva-like state than it is

in any other Insects. The males, however, are well-developed beetles;

unlike the males of Lampyrides, in general they have not peculiar eyes, but

on the other hand they possess antennae which are amongst the most highly

developed known, the joints being furnished on each side with a long

appendage densely covered with pubescence of a remarkable character. There

is no reason to doubt that Haase was correct in treating the Insect we

figure (Fig. 129, B) as a perfect Insect; he is, indeed, corroborated by

Riley.[129] The distinctions between the larva and female imago are that

the latter has two claws on the feet instead of one, a greater number of

joints in the antennae, and less imperfect eyes; the female is in fact a

larva, making a slightly greater change at the last ecdysis, than at those

previous. It is much to be regretted that we have so very small a knowledge

of these most interesting Insects. Malacodermidae are probably the most

imperfect or primitive of all beetles, and it is a point of some interest

to find that in one of them the phenomena of metamorphosis are reduced in

one sex to a minimum, while in the other they are—presumably at

least—normal in character.

Numerous larvae of most extraordinary, though diverse, shapes, bearing long

processes at the sides of the body, and having a head capable of complete

withdrawal into a slender cavity of the thorax, have long been known in

several parts of the world, and Dr. Willey recently found in New Britain a

species having these body-processes articulated. Though they are doubtless

larvae of Lampyrides, none of them have ever been reared or exactly

identified.

A very remarkable Ceylonese Insect, _Dioptoma adamsi_ Pascoe, is placed in

Lampyrides, but can scarcely belong there, as apparently it has but five or

six visible ventral segments; this Insect has two pairs of eyes, a large

pair, with coarse facets on {252}the under side of the head, and a

moderate-sized pair with fine facets on the upper side. Nothing is known as

to the habits of this curiosity, not even whether it is luminous in one or

both sexes.

It is believed that the perfect instar of Lampyrides takes no food at all.

The larvae were formerly supposed to be vegetarian, but it appears probable

that nearly all are carnivorous, the chief food being Mollusca either

living or dead. The larvae are active, and in many species look almost as

much like perfect Insects as do the imagos.

The other divisions of Malacodermidae—Lycides, Drilides, Telephorides—also

have predaceous, carnivorous larvae. All these groups are extensive. Though

much neglected by collectors and naturalists, some 1500 species of the

family Malacodermidae have been detected. We have about 50 in Britain, and

many of them are amongst the most widely distributed and abundant of our

native Insects. Thus, however near they may be to the primitive condition

of Coleoptera, it is highly probable that they will continue to exist

alongside of the primitive Cockroaches and Aptera, long after the more

highly endowed forms of Insect-life have been extinguished wholesale by the

operations of mankind on the face of the earth.

[Illustration: Fig. 130—_Malachius aeneus._ Britain. A, Larva (after

Perris); B, female imago.]

FAM. 55. MELYRIDAE (or MALACHIIDAE).—_Six visible and moveable ventral

abdominal segments; the basal part more or less distinctly co-adapted with

the coxae._ These Insects are extremely numerous, but have been very little

studied. In many works they are classified with Malacodermidae, but were

correctly separated by Leconte and Horn, and this view is also taken by Dr.

Verhoeff, the latest investigator. The smaller number of visible ventral

segments appears to be due to a change at the base correlative with an

adaptation between the base of the abdomen and the hind coxae. The

characters are singularly parallel with those of Silphidae; but in

Melyridae the antennae are filiform or serrate, {253}not clavate. The

habits in the two families are different, as the Melyridae are frequenters

of flowers. Many of the Melyridae have the integument soft, but in the

forms placed at the end of the family—_e.g._ _Zygia_—they are much firmer.

Thus these Insects establish a transition from the Malacodermidae to

ordinary Coleoptera. Although the imagos are believed to consume some

products of the flowers they frequent, yet very little is really known, and

it is not improbable that they are to some extent carnivorous. This is the

case with the larvae that are known (Fig. 130, larva of _Malachius

aeneus_). These are said by Perris to bear a great resemblance to those of

the genus _Telephorus_, belonging to the Malacodermidae.

FAM. 56. CLERIDAE.—_Tarsi five-jointed; but the basal joint of the

posterior very indistinct, usually very small above, and closely united

with the second by an oblique splice; the apices of joints two to four

usually prolonged as membranous flaps; anterior coxae prominent, usually

contiguous, rather large, but their cavities not prolonged externally;

labial palpi usually with large hatchet-shaped terminal joint; ventral

segments five or six, very mobile._ The Cleridae are very varied in form

and colours; the antennae are usually more or less clubbed at the tip, and

not at all serrate, but in _Cylidrus_ and a few others they are not

clubbed, and in _Cylidrus_ have seven flattened joints. The student should

be very cautious in deciding as to the number of joints in the feet in this

family, as the small basal joint is often scarcely distinguishable, owing

to the obliteration of its suture with the second joint. The little Alpine

_Laricobius_ has the anterior coxal cavities prolonged externally, and the

coxae receive the femora to some extent, so that it connects Cleridae and

Derodontidae. The Cleridae are predaceous, and their larvae are very

active; they are specially fond of wood-boring Insects; that of _Tillus

elongatus_ (Fig. 131) enters the burrows of _Ptilinus pectinicornis_ in

search of the larva. The members of the group Corynetides frequent animal

matter, carcases, bones, etc., and, it is said, feed thereon, but Perris's

recent investigations[130] make it probable that the larvae really eat the

innumerable Dipterous larvae found in such refuse; it is also said that the

larvae of Cleridae spin cocoons for their metamorphosis; but Perris has

also shown that the larvae of _Necrobia ruficollis_ really use the puparia

formed {254}by Diptera. Some of the species of _Necrobia_ have been spread

by commercial intercourse, and _N. rufipes_ appears to be now one of the

most cosmopolitan of Insects. The beautifully coloured _Corynetes

coeruleus_ is often found in our houses, and is useful, as it destroys the

death-watches (_Anobium_) that are sometimes very injurious. _Trichodes

apiarius_, a very lively-coloured red and blue beetle, destroys the larvae

of the honey-bee, and Lampert has reared _Trichodes alvearius_ from the

nests of _Chalicodoma muraria_, a mason-bee; he records that one of its

larvae, after being full grown, remained twenty-two months quiescent and

then transformed to a pupa. Still more remarkable is a case of fasting of

the larva of _Trichodes ammios_ recorded by Mayet;[131] this Insect, in its

immature form, destroys _Acridium maroccanum_; a larva sent from Algeria to

M. Mayet refused such food as was offered to it for a period of two and a

half years, and then accepted mutton and beef as food; after being fed for

about a year and a half thereon, it died. Some Cleridae bear a great

resemblance to Insects of other families, and it appears probable that they

resemble in one or more points the Insects on which they feed. The species

are now very numerous, about 1000 being known, but they are rare in

collections; in Britain we have only nine species, and some of them are now

scarcely ever met with.

[Illustration: Fig. 131—Larva of _Tillus elongatus_. (New Forest). A, Head;

B, front leg; C, termination of the body, more magnified.]

FAM. 57. LYMEXYLONIDAE.—_Elongate beetles, with soft integuments, front and

middle coxae exserted, longitudinal in position; tarsi slender,

five-jointed; antennae short, serrate, but rather broad._ Although there

are only twenty or thirty species of this family, they occur in most parts

of the world, and are remarkable on account of their habit of drilling

cylindrical holes in hard wood, after the manner of Anobiidae. The larva of

_Lymexylon navale_ was formerly very injurious to timber used for

constructing ships, but of late years its ravages appear to have been of

little importance. The genus _Atractocerus_ consists of a few species of

very abnormal {255}Coleoptera, the body being elongate and vermiform, the

elytra reduced to small, functionless appendages, while the wings are

ample, not folded, but traversed by strong longitudinal nervures, and with

only one or two transverse nervures. Owing to the destruction of our

forests the two British Lymexylonidae—_L. navale_ and _Hylecoetus

dermestoides_—are now very rarely met with.

[Illustration: Fig. 132—_Hydrocyphon deflexicollis._ Britain. A, Larva

(after Tournier); B, imago.]

FAM. 58. DASCILLIDAE.—_Small or moderate-sized beetles, with rather flimsy

integuments, antennae either serrate, filiform, or even made flabellate by

long appendages; front coxae elongate, greatly exserted; abdomen with five

mobile ventral segments; tarsi five-jointed._ This is one of the most

neglected and least known of all the families of Coleoptera, and one of the

most difficult to classify; though always placed amongst the Serricornia,

it is more nearly allied to Parnidae and Byrrhidae, that are placed in

Clavicornia, than it is to any of the ordinary families of Serricornia. It

is probable that careful study will show that it is not natural as at

present constituted, and that the old families, Dascillidae and Cyphonidae,

now comprised in it, will have to be separated. Only about 400 species are

at present known; but as nearly 100 of these have been detected in New

Zealand, and 17 in Britain, doubtless the numbers in other parts of the

world will prove very considerable, these Insects having been neglected on

account of their unattractive exterior, and fragile structure. The few

larvae known are of three or four kinds. That of _Dascillus cervinus_ is

subterranean, and is believed to live on roots; in form it is somewhat like

a Lamellicorn larva, but is straight, and has a large head. Those of the

Cyphonides are aquatic, and are remarkable for possessing antennae

consisting of a great many joints (Fig. 132, A). Tournier describes the

larva of _Helodes_ as possessing abdominal but not thoracic spiracles, and

as breathing by coming to the surface of the water and carrying down a

bubble of air adhering to the posterior part of the body; the larva of

_Hydrocyphon_ (Fig. 132, A) {256}possesses several finger-like pouches that

can be exstulpated at the end of the body. It is probable that these larvae

are carnivorous. The imago of this Insect abounds on the bushes along the

banks of some of the rapid waters of Scotland; according to Tournier, when

alarmed, it enters the water and goes beneath it for shelter. The third

form of larva belongs to the genus _Eucinetus_, it lives on fungoid matter

on wood, and has ordinary antennae of only four joints.[132] It is very

doubtful whether _Eucinetus_ is related to other Dascillidae; some

authorities indeed place it in Silphidae.

FAM. 59. RHIPICERIDAE.—_Tarsi five-jointed, furnished with a robust

onychium (a straight chitinous process bearing hairs) between the claws;

antennae of the male bearing long processes, and sometimes consisting of a

large number of joints. Mandibles robust, strongly curved, and almost

calliper-like in form._ This small family of less than 100 species is

widely distributed, though confined to the warmer regions of the earth, a

single species occurring in the extreme south of Eastern Europe. Very

little is known as to the natural history. The larva of _Callirhipis

dejeani_ (Fig. 133, A) is described by Schiödte as hard, cylindrical in

form, and peculiarly truncate behind, so that there appear to be only eight

abdominal segments, the ninth segment being so short as to look like an

operculum at the extremity of the body. It lives in wood.

[Illustration: Fig. 133—A, Larva of _Callirhipis dejeani_ (after Schiödte);

B, _Rhipicera mystacina_ male, Australia; C, under side of its hind foot.]

{257}[Illustration: Fig. 134—_Athous rhombeus._ New Forest. A, Larva; B,

female imago.]

FAM. 60. ELATERIDAE (_Click-beetles_).—_Antennae more or less serrate along

the inner margin, frequently pectinate, rarely filiform. Front coxae small,

spherical. Thorax usually with hind angles more or less prolonged

backwards; with a prosternal process that can be received in, and usually

can move in, a mesosternal cavity. Hind coxa with a plate, above which the

femur can be received. Visible ventral segments usually five, only the

terminal one being mobile. Tarsi five-jointed._ This large family of

Coleoptera comprises about 7000 species. Most of them are readily known by

their peculiar shape, and by their faculty of resting on the back,

stretching themselves out flat, and then suddenly going off with a click,

and thus jerking themselves into the air. Some, however, do not possess

this faculty, and certain of these are extremely difficult to recognise

from a definition of the family. According to Bertkau[133] our British

_Lacon murinus_ is provided near the tip of the upper side of the abdomen

with a pair of eversible glands, comparable with those that are better

known in Lepidopterous larvae. He states that this Insect does not try to

escape by leaping, but shams death and "stinks away" its enemy. The glands,

it would appear, become exhausted after the operation has been repeated

many times. The extent of the leap executed by click-beetles differs

greatly; in some species it is very slight, and only just sufficient to

turn the Insect right side up when it has been placed on its back. In some

cases the Insects go through the clicking movements with little or no

appreciable result in the way of consequent propulsion. Although it is

difficult to look on this clicking power as of very great value to the

Elateridae, yet their organisation is profoundly modified so as to permit

its accomplishment. The junction of the prothorax with the after-body

involves a large number of pieces which are all more or less changed, so

that the joint is endowed with greater mobility than usual; while in the

position of repose, on the other hand, the two parts are firmly locked

together. The thoracic stigma is of a highly remarkable nature, and the

extensive {258}membrane in which it is placed appears to be elastic.

Although the mechanics of the act of leaping are still obscure, yet certain

points are clear; the prosternal process possesses a projection, or notch,

on its upper surface near the tip; as a preliminary to leaping, this

projection catches against the edge of the mesosternal cavity, and as long

as this position is maintained the Insect is quiescent; suddenly, however,

the projection slips over the catch, and the prosternal process is driven

with force and rapidity into the mesosternal cavity pressing against the

front wall thereof, and so giving rise to the leap.

Several larvae are well known; indeed the "wire-worms" that are sometimes

so abundant in cultivated places are larvae of Elateridae. In this instar

the form is usually elongate and nearly cylindrical; the thoracic segments

differ but little from the others except that they bear rather short legs;

the skin is rather hard, and usually bears punctuation or sculpture; the

body frequently terminates in a very hard process, of irregular shape and

bearing peculiar sculpture on its upper surface, while beneath it the

prominent anal orifice is placed: this is sometimes furnished with hooks,

the function of which has not yet been observed. The majority of these

larvae live in decaying wood, but some are found in the earth; as a rule

the growth is extremely slow, and the life of the larva may extend over two

or more years. Some obscurity has prevailed as to their food; it is now

considered to be chiefly flesh, though some species probably attack

decaying roots; and it is understood that wire-worms destroy the living

roots, or underground stems, of the crops they damage. Various kinds of

Myriapods (see Vol. V. p. 29) are often called "wire-worm," but they may be

recognised by possessing more than six legs. The larvae of the genus

_Cardiophorus_ are very different, being remarkably elongate without the

peculiar terminal structure, but apparently composed of twenty-three

segments.

The genus _Pyrophorus_ includes some of the most remarkable of light-giving

Insects. There are upwards of 100 species, exhibiting much diversity as to

the luminous organs; some are not luminous at all; but all are peculiar to

the New World, with the exception that there may possibly be luminous

species, allied to the American forms, in the Fiji Islands and the New

Hebrides. In the tropics of America the _Pyrophorus_, or Cucujos, form one

of the most remarkable of the natural phenomena. {259}The earliest European

travellers in the New World were so impressed by these Insects that

descriptions of their wondrous display occupy a prominent position in the

accounts of writers like Oviedo, whose works are nearly 400 years old. Only

one of the species has, however, been investigated. _P. noctilucus_ is one

of the most abundant and largest of the _Pyrophorus_, and possesses on each

side of the thorax a round polished space from which light is given forth;

these are the organs called eyes by the older writers. Besides these two

eye-like lamps the Insect possesses a third source of light situate at the

base of the ventral surface of the abdomen; there is no trace of this

latter lamp when the Insect is in repose; but when on the wing the abdomen

is bent away from the breast, and then this source of light is exposed;

hence, when flying, this central luminous body can be alternately displayed

and concealed by means of slight movements of the abdomen. The young larva

of _P. noctilucus_ is luminous, having a light-giving centre at the

junction of the head and thorax; the older larva has also numerous luminous

points along the sides of the body near the spiracles. It is remarkable

that there should be three successive seats of luminescence in the life of

the same individual. The eggs too are said to be luminous. The light given

off by these Insects is extremely pleasing, and is used by the natives on

nocturnal excursions, and by the women for ornament. The structure of the

light-organs is essentially similar to that of the Lampyridae. The light is

said to be the most economical known; all the energy that is used being

converted into light, without any waste by the formation of heat or

chemical rays. The subject has been investigated by Dubois,[134] who comes,

however, to conclusions as to the physiology of the luminous processes

different from those that have been reached by Wielowiejski and others in

their investigations on Glow-worms. He considers that the light is produced

by the reactions of two special substances, luciferase and luciferine.

Luciferase is of the nature of an enzyme, and exists only in the luminous

organs, in the form, it is supposed, of extremely minute granules.

Luciferine exists in the blood; and the light is actually evoked by the

entry of blood into the luminous organ.

We have given to this family the extension assigned to it by {260}Schiödte.

Leconte and Horn also adopt this view, except that they treat Throscides as

a distinct family. By most authors Eucnemides, Throscides, and Cebrionides

are all considered distinct families, but at present it is almost

impossible to separate them on satisfactory lines. The following table from

Leconte and Horn exhibits the characters of the divisions so far as the

imago is concerned:—

Posterior coxae laminate; trochanters small.

Labrum concealed; antennae somewhat distant from the eyes,

their insertion narrowing the front Eucnemides.

Labrum visible, free; antennae arising near the eyes under

the frontal margin Elaterides.

Labrum transverse, connate with the front.

Ventral segments six; claws simple; tibial spurs well

developed. Cebrionides.

Ventral segments five; claws serrate; tibial spurs moderate.

Perothopides.

Posterior coxae not laminate; trochanters of middle and

posterior legs very long Cerophytides.

[Illustration: Fig. 135—Larva of _Fornax_ n. sp. Hawaii. A, Upper side; B,

under side: _s_ _s_, position of spiracles; C, head more enlarged; D, under

side of terminal segment; _a_, anus.]

Throscides are considered to be distinguished by the mesosternum being

impressed on each side in front for the accommodation of the posterior face

of the front coxae. The genus _Throscus_ has the antennae clavate. The

classification of the Elaterides and these forms is a matter of the

greatest difficulty, and, if the larvae are also considered, becomes even

more complex. Cebrionid larvae are different from those of any of the other

divisions, and possess laminate, not calliper-like, mandibles. The larvae

of Eucnemides (Fig. 135) are very little known, but are highly remarkable,

inasmuch as it is very difficult to find any mouth-opening in some of them,

and they have no legs. The other divisions possess very few species

compared with Elaterides. In Britain we have about sixty species of

Elaterides, four of Throscides and three of Eucnemides; _Cerophytum_ was

probably a native many years ago. Neither Perothopides {261}nor Cebrionides

are represented in our fauna; the former of these two groups consists only

of four or five North American species, and the Cerophytides are scarcely

more numerous.

FAM. 61. BUPRESTIDAE.—_Antennae serrate, never elongate; prothorax fitting

closely to the after-body, with a process received into a cavity of the

mesosternum so as to permit of no movements of nutation. Five visible

ventral segments, the first usually elongate, closely united with the

second, the others mobile. Tarsi five-jointed, the first four joints

usually with membranous pads beneath._ This family is also of large extent,

about 5000 species being known. Many of them are remarkable for the

magnificence of their colour, which is usually metallic, and often of the

greatest brilliancy; hence their wing-cases are used by our own species for

adornment. The elytra of the eastern kinds of the genus _Sternocera_ are of

a very brilliant green colour, and are used extensively as embroidery for

the dresses of ladies; the bronze elytra of _Buprestis (Euchroma) gigantea_

were used by the native chieftains in South America as leg-ornaments, a

large number being strung so as to form a circlet. The integument of the

Buprestidae is very thick and hard, so as to increase the resemblance to

metal. The dorsal plates of the abdomen are usually soft and colourless in

beetles, but in Buprestidae they are often extremely brilliant. The

metallic colour in these Insects is not due to pigment, but to the nature

of the surface. Buprestidae appear to enjoy the hottest sunshine, and are

found only where there is much summer heat. Australia and Madagascar are

very rich in species and in remarkable forms of the family, while in

Britain we possess only ten species, all of which are of small size, and

nearly all are excessively rare. The family is remarkably rich in fossil

forms; no less than 28 per cent of the Mesozoic beetles found by Heer in

Switzerland are referred to Buprestidae.

[Illustration: Fig. 136—A, Larva of _Euchroma goliath_ (after Schiödte); B,

imago of _Melanophila decostigma_. Europe.]

The larvae (Fig. 136, A) find nourishment in living vegetable matter, the

rule being that they form galleries in or under the {262}bark of trees and

bushes, or in roots thereof; some inhabit the stems of herbaceous plants

and one or two of the smaller forms have been discovered to live in the

parenchyma of leaves. A few are said to inhabit dead wood, and in Australia

species of _Ethon_ dwell in galls on various plants. Buprestid larvae are

of very remarkable shape, the small head being almost entirely withdrawn

into the very broad thorax, while the abdomen is slender.[135] A few,

however, depart from this shape, and have the thoracic region but little or

not at all broader than the other parts. The larvae of _Julodis_—a genus

that inhabits desert or arid regions—are covered with hair; they have a

great development of the mandibles; it is believed that they are of

subterranean habits, and that the mandibles are used for burrowing in the

earth. Only the newly hatched larva is, however, known.

SERIES IV. HETEROMERA.

_Tarsi of the front and middle legs with five, those of the hind legs with

four, joints._

This series consists of some 14,000 or 15,000 species. Twelve or more

families are recognised in it, but the majority of the species are placed

in the one great family, Tenebrionidae. The number of visible ventral

segments is nearly always five. Several of the families of the series are

of doubtful validity; indeed beyond that of Tenebrionidae the taxonomy of

this series is scarcely more than a convention. The larvae may be

considered as belonging to three classes; one in which the body is

cylindrical and smooth and the integument harder than usual in larvae; a

second in which it is softer, and frequently possesses more or less

distinct pseudopods, in addition to the six thoracic legs; and a third

group in which hypermetamorphosis prevails, the young larvae being the

creatures long known as Triungulins, and living temporarily on the bodies

of other Insects, so that they were formerly supposed to be parasites.

{263}FAM. 62. TENEBRIONIDAE.—_Front coxae short, not projecting from the

cavities, enclosed behind. Feet destitute of lobed joints. Claws smooth._

This is one of the largest families of Coleoptera, about 10,000 species

being already known. A very large portion of the Tenebrionidae are entirely

terrestrial, wings suitable for flight being absent, and the elytra

frequently more or less soldered. Such forms are described in systematic

works as apterous. Unfortunately no comprehensive study has ever been made

of the wings or their rudiments in these "apterous forms."[136] it is

probable that the wings, or their rudiments or vestiges, always exist, but

in various degrees of development according to the species, and that they

are never used by the great majority of the terrestrial forms. Many of the

wood-feeding Tenebrionidae, and the genera usually placed at the end of the

family, possess wings well adapted for flight. The apterous forms are

chiefly ground-beetles, living in dry places; they are very numerous in

Africa, California, and North Mexico. Their colour is nearly always black,

and this is probably of some physiological importance; the integuments are

thick and hard, and if the wing-cases are taken off, it will be found that

they are usually more or less yellow on the inner face, even when jet-black

externally; the external skeleton is very closely fitted together, the

parts that are covered consisting of very delicate membrane; the transition

between the hard and the membranous portions of the external skeleton is

remarkably abrupt. These ground-Tenebrionidae form a very interesting

study, though, on account of their unattractive appearance, they have not

received the attention they deserve.

[Illustration: Fig. 137—_Tenebrio molitor._ Europe, etc. A, Larva

(meal-worm); B, pupa (after Schiödte); C, imago.]

Many of the Tenebrionidae, notwithstanding their dark {264}colours, are

diurnal in habits, and some of them run with extreme velocity in places so

bare and desert that the means of existence of the Insects is a mystery.

Most of the Tenebrionidae, however, shun the light. The food is usually

vegetable matter, and it is apparently preferred in a very dry state. Mr.

Gahan has recently recorded that in _Praogena_ the under surface of the

head has the gular region striate for stridulating purposes. This is the

only instance known of a voice-organ in this situation, and moreover is the

only case in all the Tenebrionidae in which any sound-producing organ has

been discovered. The larvae exhibit but little variety, they are elongate

and cylindrical, with harder integument than is usual in Coleopterous

larvae; they have six thoracic legs, and at the under side of the posterior

extremity the anus serves as a very short pseudopod. The resemblance of

these larvae to those of Elateridae is considerable; but though the body is

terminated by one or two small processes, these never attain the complexity

of the terminal segment of Elateridae. The common meal-worm—_i.e._ the

larva of _Tenebrio molitor_—is a very characteristic example of the group.

The pupae are remarkable on account of peculiar projections, of varied and

irregular form, that exist on the sides of the abdominal segments. Britain

is very poor in these Insects; our list of them scarcely attains the number

of thirty species.

FAM. 63. CISTELIDAE.—_Claws comb-like._ The very obscure beetles forming

this family are only separated from Tenebrionidae on account of their

pectinate claws. About 500 species of Cistelidae are recorded; the early

instars, so far as known, do not differ from those of Tenebrionidae; the

larvae are believed to live on dead wood.

FAM. 64. LAGRIIDAE.—_Anterior coxal cavities closed, tips of the front

coxae free, claws smooth, penultimate joint of the tarsi broader, pubescent

beneath._ This family has very little to distinguish it from Tenebrionidae,

and the group Heterotarsini appears to connect the two. It is a small

family of about 200 species, widely distributed, and represented in Britain

by one species, _Lagria hirta_. The early instars are similar to those of

the Tenebrionidae, except that the larva is less retiring in its habits and

wanders about on foliage: it is of broader form than that of most of the

Tenebrionidae. The pupa has long projections at the sides of the abdominal

segments.

{265}FAM. 65. OTHNIIDAE.—Only about ten species are known of this dubious

family. They are small Insects with weak integument, and are said by

Leconte and Horn to be distinguished from "degraded Tenebrionidae" by the

more mobile abdominal segments, the hind-margins of which are

semi-membranous. The antennae are of the clubbed shape, characteristic of

"Clavicornia," but this also occurs in numerous undoubted Tenebrionidae.

Species of _Othnius_ have been found in Japan and Borneo, as well as in

North America. Nothing is known as to their metamorphoses.

FAM. 66. ÆGIALITIDAE.—_All the coxae very widely separated; no

co-adaptation between the sides of the abdomen and the edges of the

wing-cases; five ventral segments and tip of a sixth visible._ Two minute

and rare Insects from North-West America constitute this family. It is

distinguished from Pythidae by the minute front coxae, widely separated,

completely closed in, and deeply embedded in the prosternum.

FAM. 67. MONOMMIDAE.—This is a small family of less than 100 species, the

members of which have the details of their external structure much

modified, permitting the Insect to pack itself up in repose in a very

perfect manner. They are of small size and oval form; and are absent from

Europe and the Antipodes. Nothing appears to be known as to the

metamorphosis.

FAM. 68. NILIONIDAE.—_Broad, circular Heteromera, of moderate size, with

the front coxae but little separated, and the anterior acetabula closed,

though having the appearance of being open in consequence of the tips of

the epimera being free. The inflexed portion of the wing-cases remarkably

broad._ A small family of less than fifty species, found on fungi, chiefly

in South America. The metamorphoses are not known. It is of very doubtful

validity.

FAM. 69. MELANDRYIDAE.—_Head not constricted behind the eyes; anterior

acetabula not closed; claws smooth. Prothorax broad behind._ These are

loosely-fitted-together Insects, of moderate or small size, frequenting dry

wood or fungi. About 200 species are known, found chiefly in temperate

regions. The few described larvae are rather varied in their details and

cannot be generalised at present. The characters of the members of this

family require fresh investigation.

FAM. 70. PYTHIDAE.—Distinguished from Melandryidae by the {266}prothorax

being narrow behind. This is a small family of about 100 species, found in

temperate regions in connection with timber. The species of _Rhinosimus_

have the head prolonged in front of the antennae so as to form a beak. The

larva of _Pytho depressus_ is flat and has parallel sides; the body is

terminated by two widely-separated sharp processes. It is found

occasionally under the bark of firs in Scotland.

FAM. 71. PYROCHROIDAE.—Differs from Melandryidae by the head forming a very

narrow neck behind, and by the penultimate tarsal joints being broad. They

are feeble Insects, though active on the wing. They are destitute of any of

the various remarkable structures found in Mordellidae. Only about forty

species are known, and the family is confined to the north temperate

region, being best represented in Japan. _Pyrochroa rubens_ is common in

some parts of England; the larva is found under the bark of tree-stumps; it

is remarkably flat, and has the eighth abdominal segment unusually long,

while the ninth terminates the body in the form of two long sharp

processes.

FAM. 72. ANTHICIDAE.—_Head with an abrupt narrow neck; prothorax narrower

than the elytra. Middle and hind coxae placed in definite acetabula. Claws

simple._ These little Insects are numerous in species; they have little

resemblance to Pyrochroidae, though the characters of the two families

cause us to place them in proximity. There are about 1000 species known;

though we have only about 12 in Britain, they are very numerous in the

Mediterranean region. The family Pedilidae of Lacordaire and some others is

now merged in Anthicidae. Thomson and Champion, on the other hand, separate

some very minute Insects to form the family Xylophilidae, on account of

certain differences in the form of the abdomen and tarsi. The Xylophilidae

live in dead wood; the Anthicidae, on the surface of the earth, after the

manner of ground-beetles; very little is, however, known as to their

natural history.

FAM. 73. OEDEMERIDAE.—_Prothorax not forming sharp edges at the sides, head

without a narrow neck. Penultimate tarsal joint broad; claws smooth._ These

Insects usually have a feeble integument, and bear a certain resemblance to

Malacodermidae. Less than 500 species are known, but they are widely

distributed, and occur in both temperate and tropical regions. The larvae

live in old wood. _Nacerdes melanura_ is common on our {267}coasts, where

its larva lives in timber cast up by the sea, or brought down by floods,

and it is able to resist immersion by the tide. It is remarkable from the

possession of five pairs of dorsal false feet on the anterior segments, and

two pairs on the ventral aspect. In _Asclera caerulea_ there are six dorsal

and three ventral pairs of these remarkable pseudopods. We have six species

of Oedemeridae in Britain, including _Asclera_ as well as _Nacerdes_.

[Illustration: Fig. 138—_Asclera caerulea._ A, Larva; B, pupa (after

Schiödte); C, imago. Cambridge.]

FAM. 74. MORDELLIDAE (incl. RHIPIPHORIDAE).—_Head peculiarly formed, vertex

lobed or ridged behind, so that in extension it reposes on the front edge

of the pronotum; capable of great inflection and then covering the

prosternum; hind coxae with laminae forming a sharp edge behind, frequently

very large._ This family is a very distinct one, though it exhibits great

variety. Lacordaire has pointed out that Rhipiphoridae cannot at present be

satisfactorily distinguished from Mordellidae. Leconte and Horn separate

the two by the fact that the sides of the prothorax form a sharp edge in

Mordellidae, but not in Rhipiphoridae. A better character would perhaps be

found by a study of the head, but as this would clearly result in a radical

change in the composition of the two families it is preferable to treat

them at present as only sub-families: if placed on a similar basis to the

preceding families, the group would however form, not two, but several

families. Besides the unusual shape of the head (Fig. 139, D) the ventral

region of the body is remarkably formed, being very convex, and in many

Mordellides terminating in a strong spinous process (Fig. 139, C). The

elytra are, in several Rhipiphorids, of the groups Myoditini and

Rhipidiini, reduced to a very small size, and the wings are not folded. The

Mordellidae are remarkable for their activity; in the perfect state they

usually frequent flowers, and fly and run with extreme rapidity.

Mordellides are amongst the most numerous and abundant of the European

Coleoptera, and in Britain the Anaspini swarm on the flowers of bushes and

Umbelliferae. The {268}life-histories appear to be singularly varied; but

unfortunately they are incompletely known. The larvae of some of the

Mordellids have been found in the stems of plants, and derive their

nutriment therefrom. This is said by Schwarz to be undoubtedly the case

with _Mordellistena floridensis_. Coquillett has found the larvae of _M.

pustulata_ in plant-stems under circumstances that render it highly

probable that they were feeding on a Lepidopterous larva contained in the

stems; and Osborn found a similar larva that was pretty certainly a

_Mordellistena_, and fed voraciously on Dipterous larvae in the stems of a

plant. The little that is known as to the metamorphoses of _Mordella_ and

_Anaspis_ shows that they live in old wood, but does not make clear the

nature of their food.

[Illustration: Fig. 139—_Mordellistena floridensis._ America. (After

Riley.) A, Larva; B, pupa; C, imago; D, outline of detached head of imago

of _M. pumila_, to show the neck.]

Although it has been ascertained that the Rhipiphorides exhibit instances

of remarkable metamorphosis, their life-histories are still very

imperfectly known. Dr. Chapman has ascertained some particulars as to

_Metoecus paradoxus_, which has long been known to prey in the larval state

on the larvae of the common social wasps.[137] The eggs are apparently not

deposited in the nests of the wasps, but in old wood. The young larva is a

triungulin, similar to that of the Cantharidae, we shall subsequently

describe. It is not known how it makes its way to the wasps' nests, but it

is possible that when a wasp visits some old wood haunted by these larvae,

some of them may attach themselves to it and be carried to the wasps'

nests. When {269}access is gained to the cells the little _Metoecus_

pierces the skin of one of the wasp-grubs, and entering in it feeds on the

interior; after it has increased in size it emerges, changes its skin, and

assumes a different form and habits; subsequently, as an external parasite,

entirely devouring the wasp-larva, and then becoming a pupa, and finally a

perfect _Metoecus_, in the cell of the wasp. The wasps, though they

investigate the cells, do not apparently entertain any objection to the

_Metoecus_, though there may be sometimes as many as twenty or thirty of

the destroyers in a single nest. A few hours after the _Metoecus_ has

become a winged Insect and has escaped from the cells, it appears however,

from the observations of Erné[138] on nests of wasps in captivity, that the

wasps become hostile to the foreigners, and it is probable that in a state

of nature these leave the nest as quickly as possible. _Emenadia

flabellata_, a genus allied to _Metoecus_, has been discovered by Chobaut

to have a similar life-history, except that it attacks a solitary wasp of

the genus _Odynerus_.[139] An old record to the effect that a second

species of _Emenadia_, _E. bimaculata_, lives in the stalks of _Eryngium

campestre_, on the pith, is now thought to be erroneous. Fabre has found

the larvae and pupae of another Rhipiphorid in the cells of a bee,

_Halictus sexcinctus_.

The most remarkable of the Rhipiphorids, from the point of view of its

habits, is certainly _Symbius blattarum_, which is now treated as the same

as an Insect previously described by Thunberg from specimens found in amber

and called _Ripidius pectinicornis_. This species is parasitic in

cockroaches; the male and female are very different, the former being an

active winged Insect, while the female is worm-like, differing but little

from the larva, and never leaving the body of the cockroach. It is to be

regretted that the life-history is not better known. The species has been

found on board ship in vessels coming from India; the male has been met

with in several European countries, but the female is excessively rare.

FAM. 75. CANTHARIDAE OR MELOIDAE (_Blister-beetles_, _Oil-beetles_).-_-Head

with an abrupt neck; elytra and sides of the abdomen without any

coadaptation; each claw of the feet with a long appendage closely applied

beneath it._ This distinct family consists of Heteromera with soft

integument, and is remarkable for the fact that many of its members contain

a substance that when extracted {270}and applied to the human skin,

possesses the power of raising blisters. The life-history is highly

remarkable, the most complex forms of hyper-metamorphosis being exhibited.

The species now known amount to about 1500; there can be no difficulty in

recognising a member of the family by the above characters, except that in

a very few cases each claw bears a projecting tooth, instead of an elongate

appendage parallel with itself. The penultimate tarsal joint scarcely ever

broader than the preceding; the colour and style of markings are extremely

varied. There are two very distinct sub-families, Cantharides and Meloides;

the former are winged Insects, and are frequently found on flowers or

foliage. The Meloides are wingless, and consequently terrestrial; they have

a very short metasternum, so that the middle coxae touch the hind; and they

also have very peculiar wing-cases, one of the two overlapping the other at

the base; in a few Meloids the wing-cases are merely rudiments.

The post-embryonic development of these Insects is amongst the most

remarkable of modern entomological discoveries. The first steps were made

by Newport in 1851,[140] and the subject has since been greatly advanced by

Fabre, Riley, and others. As an example of these peculiar histories, we may

cite Riley's account[141] of _Epicauta vittata_ (Fig. 140), a

blister-beetle living at the expense of North American locusts of the genus

_Caloptenus_. The locust lays its eggs underground, in masses surrounded by

an irregular capsule, and the _Epicauta_ deposits its eggs in spots

frequented by the locust, but not in special proximity to the eggs thereof.

In a few days the eggs of the blister-beetle hatch, giving rise to little

larvae of the kind called triungulin (Fig. 140, A), because each leg is

terminated by three tarsal spines or claws. In warm, sunny weather these

triungulins become very active; they run about on the surface of the ground

exploring all its cracks, penetrating various spots and burrowing, till an

egg-pod of the locust is met with; into this the triungulin at once eats

its way, and commences to devour an egg. Should two or more triungulins

enter the same egg-pod, battles occur till only one is left.

{271}[Illustration: FIG. 140.—Hypermetamorphosis of _Epicauta vittata_.

North America. (After Riley.) A, Young larva or triungulin; B, Caraboid

instar or second larva; C, coarctate larva, or instar between the

Scarabaeoid and Scolytoid larva; D, Scarabaeoid larva, from which the

Scolytoid, or sixth, instar differs but little; E, pupa; F, imago.]

After a few days passed in devouring a couple of eggs, the triungulin sheds

its skin and appears as a different larva (Fig. 140, B), with soft skin,

short legs, small eyes, and different form and proportions; a second moult

takes place after about a week, but is not accompanied by any very great

change of form, though the larva is now curved, less active, and in form

like a larva of Scarabaeidae; when another moult occurs the fourth instar

appears as a still more helpless form of larva (Fig. 140, D), which

increases rapidly in size, and when full grown leaves the remains of the

egg-pod it has been living on, and forms a small cavity near by; here it

lies on one side motionless, but gradually contracting, till the skin

separates and is pushed down to the end of the body, disclosing a

completely helpless creature that has been variously called a semi-pupa,

pseudo-pupa, or coarctate larva (Fig. 140, C); in this state the winter is

passed. In spring the skin of the coarctate larva bursts, and there crawls

out of it a sixth instar which resembles the fourth (Fig. 140, D), except

in the somewhat reduced size and greater whiteness. It is worthy of remark

that the skin it has deserted retains its original form almost intact. In

this sixth instar the larva is rather active and burrows about, {272}but

does not take food, and in the course of a few days again moults and

discloses the true pupa (Fig. 140, E). As usual in Coleoptera this instar

lasts but a short time, and in five or six days the perfect beetle appears

(Fig. 140, F). It is extremely difficult to frame any explanation of this

complex development; there are, it will be noticed, no less than five

stages interposed between the first larval instar and the pupal instar, and

the creature assumes in the penultimate one a quasi-pupal state, to again

quit it for a return to a previous state. It is possible to look on the

triungulin and the pupal instars as special adaptations to external

conditions; but it is not possible to account for the intermediate instars

in this way, and we must look on them as necessitated by the physiological

processes going on internally. Nothing, however, is known as to these. It

may be well to mention that, after describing and figuring (_loc. cit._)

this series of instars, Riley changed his views as to their

nomenclature.[142] The following summary of the metamorphosis, to which we

have added the two nomenclatures of Riley—the original one, when different

from the amended one, being given in square brackets—may therefore be

useful, viz.—Egg; 1, triungulin-larva—moult; 2, Caraboid larva [second

larva, Caraboid stage]—moult; 3, Scarabaeoid larva [second larva,

Scarabaeoid stage]—moult; 4, Scarabaeoid larva [second larva, ultimate

stage] (large amount of food and much growth)—moult; 5, coarctate larva

[pseudo-pupa, or semipupa]; 6, Scolytoid larva [third larva] (active, but

little or no food taken)—moult; 7, pupa—moult; 8, perfect Insect.

M. Fabre has succeeded in elucidating the history of _Sitaris humeralis_, a

Cantharid that lives at the expense of bees of the genus _Anthophora_.[143]

The eggs of the _Sitaris_ are deposited in the earth in close proximity to

the entrances to the bees' nests, about August. They are very numerous, a

single female producing, it is believed, upwards of 2000 eggs. In about a

month—towards the end of September—they hatch, producing a tiny triungulin

of black colour; the larvae do not, however, move away, but, without taking

any food, hibernate in a heap, remaining in this state till the following

April or May, when they become active. Although they are close to the

abodes of the bees they do not enter them, but seek to attach themselves

{273}to any hairy object that may come near them, and thus a certain number

of them get on to the bodies of the _Anthophora_ and are carried to its

nest. They attach themselves with equal readiness to any other hairy

Insect, and it is probable that very large numbers perish in consequence of

attaching themselves to the wrong Insects. The bee in question is a species

that nests in the ground and forms cells, in each of which it places honey

and lays an egg, finally closing the receptacle. It is worthy of remark

that in the case of the _Anthophora_ observed by M. Fabre, the male appears

about a month before the female, and it is probable that the vast majority

of the predatory larvae attach themselves to the male, but afterwards seize

a favourable opportunity, transfer themselves to the female, and so get

carried to the cells of the bee. When she deposits an egg on the honey, the

triungulin glides from the body of the bee on to the egg, and remains

perched thereon as on a raft, floating on the honey, and is then shut in by

the bee closing the cell. This remarkable act of slipping on to the egg

cannot be actually witnessed, but the experiments and observations of the

French naturalist leave little room for doubt as to the matter really

happening in the way described. The egg of the bee forms the first

nutriment of the tiny triungulin, which spends about eight days in

consuming its contents; never quitting it, because contact with the

surrounding honey is death to the little creature, which is entirely

unfitted for living thereon. After this the triungulin undergoes a moult

and appears as a very different creature, being now a sort of vesicle with

the spiracles placed near the upper part; so that it is admirably fitted

for floating on the honey (Vol. V. Fig. 86, 10). In about forty days, that

is, towards the middle of July, the honey is consumed, and the vesicular

larva after a few days of repose changes to a pseudo-pupa (11 of the fig.

cited) within the larval skin. After remaining in this state for about a

month, some of the specimens go through the subsequent changes, and appear

as perfect Insects in August or September. The majority delay this

subsequent metamorphosis till the following spring, wintering as

pseudo-pupae and continuing the series of changes in June of the following

year; at that time the pseudo-pupa returns to a larval form (12 of the fig.

cited), differing comparatively little from the second instar. The skin,

though detached, is again not shed, so that this ultimate larva is enclosed

in two {274}dead skins; in this curious envelope it turns round, and in a

couple of days, having thus reversed its position, becomes lethargic and

changes to the true pupa, and in about a month subsequent to this appears

as a perfect Insect, at about the same time of the year as it would have

done had only one year, instead of two, been occupied by its metamorphosis.

M. Fabre employs the term, third larva, for the instar designated by Riley

Scolytoid larva, but this is clearly an inconvenient mode of naming the

instar. _Sitaris humeralis_ is now very rare in Britain, but it seems

formerly to have been more common, and it is not improbable that its

triungulin may have been the "_Pediculus melittae_," that was believed by

Kirby to be a sort of bee-louse. Some species of the genus _Meloe_ are

still common in Britain, and the Insects may be seen with heavy distended

abdomen grazing on herbage in the spring. The females are enormously

prolific, a single one producing, it is believed, about 10,000 eggs.

_Meloe_ is also dependent on _Anthophora_, and its life-history seems on

the whole to be similar to that of _Sitaris_; the eggs are, however, not

necessarily deposited in the neighbourhood of the bees' nests, and the

triungulins distribute themselves on all sorts of unsuitable Insects, so

that it is possible that not more than one in a thousand succeeds in

getting access to the _Anthophora_ nest. It would be supposed that it would

be a much better course for these bee-frequenting triungulins to act like

those of _Epicauta_, and hunt for the prey they are to live on; but it must

be remembered that they cannot live on honey; the one tiny egg is their

object, and this apparently can only be reached by the method indicated by

Fabre. The history of these Insects certainly forms a most remarkably

instructive chapter in the department of animal instinct, and it is a

matter for surprise that it should not yet have attracted the attention of

comparative psychologists. The series of actions, to be performed once and

once only in a lifetime by an uninstructed, inexperienced atom, is such

that we should _a priori_ have denounced it as an impossible means of

existence, were it not shown that it is constantly successful. It is no

wonder that the female _Meloe_ produces 5000 times more eggs than are

necessary to continue the species without diminution in the number of its

individuals, for the first and most important act in the complex series of

this life-history is accomplished by an extremely indiscriminating

instinct; the {275}newly hatched _Meloe_ has to get on to the body of the

female of one species of bee; but it has no discrimination whatever of the

kind of object it requires, and as a matter of fact, passes with surprising

rapidity on to any hairy object that touches it; hence an enormous majority

of the young are wasted by getting on to all sorts of other Insects; these

larvae have been found in numbers on hairy Coleoptera as well as on flies

and bees of wrong kinds; the writer has ascertained by experiment that a

camel's-hair brush is as eagerly seized, and passed on to, by the young

_Meloe_ as a living Insect is.

The histories of several other Cantharids have been more or less completely

discovered. Fabre has found the larva of _Cerocoma schaefferi_ attacking

the stores of provisions laid up by a fossorial wasp of the genus

_Tachytes_, and consisting of Orthoptera of the family Mantidae. The

student who wishes for further information may refer to M. Beauregard's

work on this family.[144]

Some half-dozen species of the genus _Cephaloon_ found in Siberia, Japan,

and North America, have, by some authorities, been separated as the family

Cephaloidae. Nothing is known as to the metamorphosis of these rare

beetles; and at present it is not necessary to distinguish them from

Cantharidæ.

FAM. 76. TRICTENOTOMIDAE.—_Large Heteromera, with powerful free projecting

mandibles; the antennae long, but with the terminal three joints short,

with angular projections on one side._ This family includes only two genera

and seven or eight species. They are very remarkable Insects; _Autocrates

aenea_ being three inches long. The family is of considerable interest, as

it seems to have no affinity with any other Coleoptera. The appearance of

the species somewhat reminds one of Lucanidae, or Prionides; but

Trictenotomidae have even less relation to those beetles than they have to

the members of the Heteromerous series. The Trictenotomidae appear to be

found only in the primitive forests of the Indian and Indo-Malayan regions.

Nothing is known as to their life-histories.

{276}SERIES V. PHYTOPHAGA.

_Tarsi apparently four-jointed, the three basal joints usually densely

set with cushion-like pubescence beneath; the third joint different in

form, being divided into two lobes, or grooved on its upper surface so as

to allow of the fourth joint being inserted near its base instead of at

its extremity. Head not forming a definite prolonged beak; its labrum

visible, the palpi rarely (and even then not completely) occluded in the

mouth._