[Illustration: FIG. 179.—_Tettix bipunctatus._ Britain. A, The Insect

magnified; B, part of the middle of the body; _a_, prolongation of

pronotum; _b_, tegmen; _c_, wing.]

The tribe Tettigides is a very extensive group of small Acridiidae, in

which the pronotum extends backwards as a hood and covers the body, the

tegmina and wings being more or less modified. In our British species (Fig.

179) this condition does not greatly modify the appearance of the Insect,

but in many exotic species (Fig. 180) the hood assumes {301}remarkable

developments, so that the Insects have no longer the appearance of

Orthoptera. It would be impossible, without the aid of many figures, to

give an idea of the variety of forms assumed by this prothoracic expansion.

It is a repetition of what occurs in the Order Hemiptera, where the

prothoracic hoods of the Membracides exhibit a similar, though even more

extraordinary, series of monstrous forms. So great is the general

similarity of the two groups that when the genus _Xerophyllum_ (Fig. 180,

A) was for the first time described, it was treated by the describer as

being a bug instead of a grasshopper. This genus includes several species

from Africa. The curious _Cladonotus_ (Fig. 180, B) is a native of Ceylon,

where it is said to live in sandy meadows, after the fashion of our

indigenous species of _Tettix_ (Fig. 179). Very little is known as to the

habits of these curious Tettigides, but it has been ascertained that some

of the genus _Scelimena_ are amphibious, and do not hesitate to enter the

water and swim about there; indeed it is said that they prefer plants

growing under water as food. This habit has been observed both in Ceylon

and the Himalayas. The species are said to have the hind legs provided with

dilated foliaceous appendages useful for swimming.

[Illustration: FIG. 180.—Tettigides: A, _Xerophyllum simile_ Fairm.; B,

_Cladonotus humbertianus_. (After Bolivar.)]

[Illustration: FIG. 181.—A, _Mastax_ (_Erianthus_) _guttatus_, male.

Sumatra. (After Westwood.) B, profile; C, front of head.]

The tribe Mastacides includes thirty or forty species of Acridiidae with

short antennae and vertical head (Fig. 181, _Mastax guttatus_); they are

apparently all rare and little {302}known, but are widely distributed in

the tropics of the Old and New Worlds. Nothing whatever seems to be known

of their habits or of their development.

The tribe Pneumorides includes a still smaller number of species of very

aberrant and remarkable grasshoppers, of large size, with short antennae,

and with the pronotum prolonged and hood-like; they are peculiar to South

Africa. Although amongst the most remarkable of Insects, we are not able to

give any information as to their habits. It would appear from the form of

their legs that they have but little power of hopping. The species of which

we figure the female (Fig. 182) is very remarkable from the difference in

colour of the sexes. The female is so extravagantly coloured that she has

been said to look as if "got up" for a fancy-dress ball. She is of a gay

green, with pearly white marks, each of which is surrounded by an edging of

magenta; the white marks are very numerous, especially on the parts of the

body not shown in our figure; the face has magenta patches and a large

number of tiny pearly-white tubercles, each of which, when placed on a

green part, is surrounded by a little ring of mauve colour. Though the

female is certainly one of the most remarkably coloured of Insects, her

consort is of a modest, almost unadorned green colour, and is considerably

different in form. He is, however, provided with a musical apparatus, which

it is possible may be a means of pleasing his gorgeous but dumb spouse. It

consists of a series of ridges placed on each side of the inflated abdomen,

which, as we have previously (p. 200) remarked, has every appearance of

being inflated with the result of improving its resonance.

[Illustration: FIG. 182.—_Pneumora scutellaris_, female. South Africa.]

{303}The Pyrgomorphides[235] is a small tribe of about 120 described

species, two of which are found in the south of Europe (Fig. 183,

_Pyrgomorpha grylloides_). The tribe includes a number of large and curious

Insects, among them the species of _Phymateus_ and _Petasia_, with peculiar

excrescences on the pronotum and vivid colours on some parts of the body or

its appendages, which are apparently common Insects in South Africa.

The tribe Tryxalides includes a great many species of grasshoppers. In them

the front of the head joins the upper part at an acute angle (Figs. 165 and

173). This tribe and the Acridiides are the most numerous in species of the

family. To the latter belong most of the migratory locusts of the New World

(Fig. 175, _Caloptenus spretus_). A Spanish species of this tribe,

_Euprepocnemis plorans_, though provided with well-developed wings,

possesses the remarkable habit of seeking shelter by jumping into the water

and attaching itself below the surface to the stems of plants.

[Illustration: FIG. 183.—_Pyrgomorpha grylloides._ South Europe. (After

Fischer.)]

[Illustration: FIG. 184.—_Xiphocera_ (_Hoplolopha_) _asina_. S. Africa.

(After de Saussure.)]

The tribe Pamphagides[236] includes some 200 species, found chiefly in

Africa and the arid regions near the Mediterranean Sea. They are mostly

apterous forms, and this circumstance has, according to de Saussure,

exercised a marked influence on the geographical distribution of the

species. Although the tribe consists chiefly of apterous forms, several

species possess {304}well-developed wings; sometimes this is the case of

the male but not of the female. Some of the species are highly modified for

a desert life, and exhibit a great variation in the colour of the

individuals in conformity with the tint of the soil they inhabit.

_Xiphocera asina_ (Fig. 184) is thought by Péringuey to be the prey of the

extraordinary South African tiger-beetles of the genus _Manticora_.

We have already mentioned the tribe Oedipodides[237] as including most of

the species of migratory locusts of the Old World. Some striking cases of

variation in colour occur amongst the winged Oedipodides. In certain

species the hind wings may be either blue or rosaceous in colour; it is

thought that the latter is the tint natural in the species, and that it is

due to the mixture of a red pigment with the pale blue colour of the wing;

hence the blue-coloured wings are analogous to cases of albinism. But the

most remarkable fact is that this colour difference is correlative with

locality. Brunner von Wattenwyl says[238] that the blue variety of _Oe.

variabilis_ occurs only in a few localities in Europe—he mentions Vienna

and Sarepta,—and that where it occurs not a single red example can be met

with. Similar phenomena occur in other species in both Europe and North

America, and L. Bruner has suggested[239] that the phenomena in the latter

country are correlative with climatic conditions.

The group Eremobiens, a subdivision of Oedipodides, includes some of the

most interesting forms of Acridiidae. Its members have several modes of

stridulation. _Cuculligera flexuosa_ and other of the winged forms,

according to Pantel,[240] produce sounds by the friction of the middle

tibia against the wing, both of these parts being specially modified for

the purpose in the male sex. The most peculiar members of the Eremobiens

are some very large Insects, modified to an extraordinary extent for a

sedentary life in deserts and arid places. Trimen says[241] that a South

African species, _Trachypetra bufo_, which lives amongst stones, is so

coloured that he had much difficulty in detecting it, and that he noticed

in certain spots, often only a few square yards in extent, where the stones

lying on the ground were darker, lighter, or more mottled than usual, that

the individuals of the grasshopper were of a similar colour to the stones.

{305}[Illustration: FIG. 185.—_Methone anderssoni_, female. S. Africa. _a_,

Front of head; _b_, posterior leg; _c_, _d_, front and hind feet. (_c_ and

_d_ magnified, the others natural size.)]

The Insect referred to by Trimen is, we believe, the _Batrachotettix whiti_

of de Saussure. In this species the alar organs are completely absent, and

the pronotum forms a sort of hood that protects the base of the hind body.

Some of the desert Eremobiens vary so much that the differences found among

individuals of the same species {306}are said by Brunner and de Saussure to

be so great as to affect even the generic characters, and give rise to the

idea of an "uncompleted species-formation."

[Illustration: FIG. 186.—Portions of middle of the body and hind leg of

_Methone anderssoni_ ♂: _a_, femur; _b_, an inferior fold; _c_,

rattling-plate; _d_, striated surface; _e_, the adjoining sculpture; _f_,

grooved portion of tegmen. The part _e_ is really, like _d_, a portion of

the second abdominal segment, not of the third, as might be supposed from

the figure.]

_Methone anderssoni_, an inhabitant of the Karoo Desert of South Africa, is

one of the largest of the Acridiidae. A female of this species is

represented of the natural size in Fig. 185. This Insect is remarkable on

account of the complex organs for producing sound, and for the great

modification of the posterior legs (Fig. 185, _b_), which do not possess

locomotive functions, but serve as a portion of the sound-producing

apparatus, and as organs for protecting the sides of the body. This Insect

is said to be very efficient in making a noise. The sexes differ

considerably in their sound-producing organs, a portion of which are

present in the female as well as in the male (Fig. 186). Connected with the

first abdominal segment, but extending backwards on the second, there is a

peculiar swelling bearing two or three strongly raised chitinous folds

(Fig. 186, _c_). When the leg is rotated these folds are struck by some

peg-like projections situate on the inner face of the base of the femur,

and a considerable noise is thus produced. The pegs cannot be seen in our

figure. This apparatus is equally well developed in female and male. On the

second abdominal segment, immediately behind the creaking folds we have

described, there is a prominent area, densely and finely striated (Fig.

186, _d_): this is rubbed by some fine asperities on the inner part of the

femur near its base. Sound is produced by this friction on the striated

surface, the sculpture of which is abruptly contrasted with that of the

contiguous parts: these structures seem to be somewhat better developed in

the male than they are in the female, and to be phonetic, at any rate in

the former sex. {307}The male has the rudimentary tegmina (Fig. 186, _f_)

much longer than they are in the female (Fig. 185), and their prolonged

part is deeply grooved, so as to give rise to strong ridges, over which

plays the edge of the denticulate and serrate femur. There is nothing to

correspond to this in the female, and friction over the surface of this

part of the male produces a different and louder sound. There can be little

doubt that this is a phonetic structure peculiar to the male. It

approximates in situation to the sound-producing apparatus of the males of

the Stenobothri and other Acridiidae. _Methone anderssoni_ has large

tympanal organs: the small tegmina cover them up completely. In the female

the tips of the tegmina seem to be adapted for forming covering-flaps for

the tympana. In both sexes there is a sac (Fig. 186, _b_) adjoining the

structures we have mentioned, but which is not directly phonetic, though it

may be an adjunct of the apparatus.

There is no other Orthopteron in which the phonetic organs are so complex

as they are in the male of _Methone anderssoni_, and it would appear

probable that this Insect possesses the power of producing two, if not

more, distinct sounds, one in common with the female, and peculiar to this

and one or two other species; the other somewhat similar to that of other

Acridiids, and more specially developed in the male, if not absolutely

confined to it.

This Insect is of a very sedentary disposition, and when disturbed

apparently seeks safety rather by the noise it can make than by flight. Its

powers of locomotion indeed are very feeble. The alar organs are quite

rudimentary, and of no assistance whatever for movement. The hind legs seem

to be almost equally useless for this purpose; they are broader than they

are in other Acridiidae, and have different functions. When _Methone_ moves

it does so by means of the anterior four legs, on which it walks propped up

as if on stilts. When at rest the hind legs are pressed close to the body,

and the tibiae are inflexed and not seen, the creature in this position

greatly resembling a clod of earth. We know nothing of the life history of

this Insect, except that the young resemble the adult in appearance, and

are provided with the sound-producing apparatus, or some portion thereof.

The geographical distribution of the Eremobiens corresponds with that of

the Pamphagides, with two important differences, viz. that in the Old World

the former group occupies a somewhat {308}more restricted area, and that it

is represented in the New World by two peculiar North American genera,

_Haldmanella_ and _Brachystola_. _B. magna_ is an Insect nearly equal in

size to _Methone anderssoni_. Its peculiar form and movements have procured

for it in Texas and Colorado the popular names of "buffalo hopper" and

"lubber grasshopper." This Insect has not—like _Methone_—the colours of the

desert sands; it is of a green tint, with comparatively smooth body, and

during the day rests concealed under tufts of grass. It has apparently no

sound organs, though de Saussure thinks there are structures present that

are vestiges or rudiments thereof.

The family Acridiidae includes a large part of the species that make up our

meagre list of British Orthoptera. Indeed, the only native Orthoptera at

the present time sufficiently common to attract general attention are, in

addition to the earwig, the species of the genera _Stenobothrus_ and

_Gomphocerus_, whose musical instruments we have described previously. We

have eight species of these Insects. They are the little grasshoppers, so

common in our fields and gardens, the hunting of which is a source of much

amusement to children. The Insect goes off with a sudden and long hop just

as it is going to be seized, and this is appreciated by the child as very

clever. The hunt, as a rule, does not result in much damage to the

grasshoppers, the ingenious escape being the greater part of the pleasure.

These _Stenobothri_ are remarkable for their variation in colour, and it is

thought by some that they frequent spots where they find themselves a match

with their surroundings. There is, however, little or no information of

importance on this point extant. _Mecostethus grossus_ (Fig. 173), though

larger, is very like the common field grasshoppers, but appears to have

become rare since the fens were drained. The two curious little

grasshoppers of the genus _Tettix_ (Fig. 179) are not uncommon. In addition

to these Acridiidae, three species of migratory locusts are occasionally

met with in Britain, viz. _Pachytylus cinerascens_ (Fig. 177), _P.

migratorius_, and _Schistocerca peregrina_ (Fig. 84); this latter we have

already alluded to as being probably the locust mentioned in the book of

Exodus.

Acridiidae have never been found in amber, owing possibly to their large

size and strength. There are but few fossil forms known, and these do not

extend farther back in time than the Mesozoic {309}epoch. Several forms,

including three peculiar genera, have been found in the Tertiary strata at

Florissant. The remains from the Mesozoic layers are apparently very

fragmentary and obscure.

Brongniart has instituted a family of Insects under the name

Palaeacrididae[242] for some fossil Insects from the Carboniferous strata

at Commentry. He considers that these Insects were abundant in the epoch of

the Carboniferous strata.

The very large number of genera and species of Acridiidae have been

recently arranged in nine tribes by Brunner von Wattenwyl:—

1. Feet without a claw-pad.[243] [Pronotum covering all the body.]

Tegmina lobe-like. Tribe 1. TETTIGIDES. (Figs. 179, 180, _Tettix_,

_Xerophyllum_, _Cladonotus_.)

1′. Feet with a claw-pad.

2. Antennae shorter than the anterior femora.

3. Head short, as if compressed from in front.

4. Body bladder-like, inflated.[244] [Pronotum covering half the

abdomen.] South African species. Tribe 2. PNEUMORIDES. (Fig. 182,

_Pneumora scutellaris_.)

4′. Body ordinary. Tribe 3. MASTACIDES. (Fig. 181, _Mastax

guttatus_.)

3′. Head very elongate. [Body apterous or sub-apterous.] Tribe 4.

PROSCOPIIDES. (Fig. 178, _Cephalocoema lineata_.)

2′. Antennae longer than the anterior femora.

3. Prosternum unarmed.

4. The plane of the vertex of the head meeting the plane of the

front of the head as an angle. The former produced or declivous.

The face looking down. Tribe 5. TRYXALIDES. (Fig. 165, _Tryxalis

nasuta_; Fig. 173, _Mecostethus grossus_.)

4′. Planes of the vertex and front of the head connected in a

rounded manner. Face looking forwards. Tribe 6. OEDIPODIDES.

(Fig. 177, _Pachytylus_; Fig. 185, _Methone_.)

3′. Prosternum with an elevated lamina in front, either irregularly

swollen or mucronate.

4. Foveoles of the vertex superior, contiguous, forming the apex of

the vertex. Face looking much downwards. Tribe 7. PYRGOMORPHIDES.

(Fig. 183, _Pyrgomorpha grylloides_.)

4′. Foveoles of the vertex, either superior (but not forming the

apex of the vertex), or lateral, or inferior, or quite obsolete.

{310}5. Foveoles superior, open behind. Prosternum irregularly

swollen, rarely mucronate. Tribe 8. PAMPHAGIDES. (Fig. 184,

_Xiphocera asina_.)

5′. Foveoles lateral or inferior, closed behind or (usually)

entirely obsolete. Prosternum distinctly mucronate or

tuberculate. Tribe 9. ACRIDIIDES. (Fig. 84, _Acridium

peregrinum_; Fig. 176, _Caloptenus spretus_.)

{311}CHAPTER XIII

ORTHOPTERA _CONTINUED_—LOCUSTIDAE, GREEN GRASSHOPPERS, KATYDIDS

FAM. VII. LOCUSTIDAE—GREEN GRASSHOPPERS.

_Orthoptera, with very long delicate antennae composed of many more than

thirty joints; hind legs longer than the others, thicker at the base.

Tarsi with four joints. Front tibiae usually provided with tympanal

organs placed below the knee; stridulating apparatus of males, when

present, situate on the basal part of the tegmina. Females usually with

an elongate exserted ovipositor, formed by the apposition of six pieces.

Wingless forms numerous._

[Illustration: FIG. 187.—_Cyrtophyllus crepitans_, male. West Indies.]

An unfortunate confusion has long existed as to the term Locustidae, and

has resulted in the application of the name to a group of Insects that

contains none of the locusts of ordinary language. Some entomologists

therefore use the term Phasgonuridea for this family, but the great

majority prefer the term Locustidae.

{312}[Illustration: FIG. 188.—Development of wings in _Platycleis grisea_:

A, B, C, D, E, consecutive stages; _p_, prothorax; _m_, mesothorax; _mt_,

metathorax; _t_, tegmen; _w_, wing; _ab′_, position of first abdominal

segment. In C, D, and E, _m_ points to the part by which the _m_, shown in

A and B, is concealed; in D and E only the positions of _mt_ are indicated.

(After Graber.)]

The Locustidae are, as a rule, more fragile Insects than the Acridiidae,

from which they can be readily distinguished by the characters we have

mentioned in our definition. According to Dufour, there are no air vesicles

connected with the tracheal system in this family; possibly to this it may

be due that none of the family undertake the long flights and migratory

wanderings that have made some of the Acridiidae so notorious. Very little

is known as to the life histories of the members of this extensive family

of Orthoptera. Graber, however, has given some particulars as to the

development of _Platycleis grisea_, and of one or two other species. He

recognises five instars, but his first is probably really the second, as he

did not observe the Insect in its youngest condition. Although his figures

are very poor, we reproduce them, as they give some idea of the mode of

growth of the wings, and of the correlative changes in the thoracic

segments. It will be seen that in the first three of these instars the alar

organs appear merely as prolongations of the sides of the posterior two

thoracic rings, and that in D a great change has occurred in the position

of these segments, so that the alar organs are free processes, the two

posterior thoracic rings being insignificant in size in comparison with the

now greatly developed prothorax. In E the tegmen is shown fully developed,

the positions of some {313}of the rings covered by it being indicated by

the letters _m_, _mt_, _ab′_. These changes are very similar to those we

have described in Acridiidae, the chief difference being the greater

development of the dependent wing-pads previous to the fourth instar.

[Illustration: FIG. 189.—Front of head of _Copiophora cornuta_, female.

Demerara.]

The ocelli in Locustidae are much more imperfect than they are in

Acridiidae, and are frequently rudimentary or nearly totally absent, or

there may be but one instead of three. They are, however, present in a

fairly well-developed state in some species, and this is the case with the

one whose face we portray in Fig. 189, where the anterior of the three

ocelli is quite conspicuous, the other two being placed one on each side of

the curious frontal cone near its base. The peculiar head ornament shown in

this figure exists in both sexes, and something similar occurs in a large

number of Conocephalides. We have not the slightest idea of its import.

Individuals of one or more species of this curious South American genus are

occasionally met with alive in gardens near London. They are, no doubt,

imported as eggs, for they are sometimes met with in the juvenile state,

but in what way they are introduced is not known.

The ovipositor frequently attains a great length in these Insects, so as to

exceed that of the body. It is used in different ways, some of the family

depositing their eggs in the earth, perhaps in vegetable matter under the

surface; but other species place the ova in twigs or stems of plants,

arranging them in a very neat and compact manner in two series, as depicted

by Riley[245] in the case of _Microcentrum retinerve_ (Fig. 190). These

eggs are laid in the autumn, and in the following spring become more

swollen before hatching. The Insect undergoes a moult during the process of

emerging from the egg. By the time the emergence is completed the

_Microcentrum_ has expanded so much {314}in size that it is a matter of

astonishment how it can ever have been packed in the egg; the young

commence jumping and eating leaves in a few minutes. Including the ecdysis

made on leaving the egg, they cast their skins five times. The

post-embryonic development occupies a period of about ten weeks. The larvae

eat their cast skins. When the final moult occurs the tegmina and wings are

at first quite soft and colourless, but within an hour they assume their

green colour. These Insects, as remarked by Riley, make interesting pets.

The people of the Amazon valley are in the habit of keeping a species in

cages, and our British _Locusta viridissima_ does very well in confinement.

One of the most curious habits of these Locustidae is a constant licking of

the front paws. Riley says that _M. retinerve_ bestows as much attention on

its long graceful antennæ as many a maiden does upon her abundant tresses,

the antennæ being drawn between the jaws and smoothed by the palpi. This

American naturalist also tells us that he reared three successive broods in

confinement, and that the Insects gradually deteriorated, so that the eggs

of the third generation failed to hatch.

[Illustration: FIG. 190.—Eggs of Katydid (_Microcentrum retinerve_): A, the

two series at deposition; B, side view of a single series. (After Riley.)]

The ovipositor, which is one of the most characteristic features of the

Locustidae, is not present in the newly-hatched Locustid (Fig. 191, A), the

organ being then represented only by two papillae placed on the penultimate

segment. The structure and development of the ovipositor in _Locusta

viridissima_ have been described by Dewitz.[246] Fig. 191, A, shows the

young Insect taken from the egg just as it is about to emerge. The abdomen

consists of ten segments, the terminal one bearing at its extremity two

processes, the cerci, _a′_. These persist throughout the life of the

Insect, and take no part in the formation of the ovipositor. The tenth

segment subsequently divides into two (_a_, _a'′_, Fig. 191, C), giving

rise to the appearance of eleven abdominal segments, and of the ovipositor

springing from the antepenultimate.

{315}[Illustration: FIG. 191.—Development of ovipositor of _Locusta

viridissima_: _a_, terminal segment; _a′_, cerci; _a″_, secondary division

of terminal segment; _b_, penultimate (ninth) segment; _b′_, primary

papillae of this segment; _b″_, secondary divisions thereof; _c_, eighth

segment; _c′_, its papillae. (After Dewitz.) A, embryo ready for emergence;

B, portion of integument of the ventral plates of eighth and ninth

segments; C, the appendages in a condition somewhat more advanced than they

are in A.]

[Illustration: FIG. 192.—Structure of ovipositor of _Locusta viridissima_:

A, arrangement of parts at base, _c′_ being separated and turned outwards;

B, transverse section. The parts of the appendage bear the same lettering

as in Fig. 191. (After Dewitz.)]

Near to one another, on the middle of the ventral aspect of the true ninth

abdominal segment, are seen the two papillae (_b′_), which at first are the

only visible indications of the future ovipositor. If, however, the

integument be taken off and carefully examined, it will be found that there

exist on the eighth abdominal plate two spots, where there is a slight

thickening and prominence of the integument (Fig. 191, B, _c_). From these

two spots the two lower rods of the ovipositor are produced; these two,

together with the two growths from the ninth segment, form the four

external rods of the ovipositor. Inside these there exist in the completed

structure two other rods (Fig. 192, B, _b'′_). These are produced by a

growth from the inner parts of the two papillae of the ninth segment. The

relations of the six rods in their early condition are shown in Fig. 191,

C, where the two primary papillae _b′_ of the ninth segment are seen with

their secondary offshoots _b″_; _c′_ being the papillae of the eighth

segment. The subsequent relations of the pieces are shown in Fig. 192; A

exhibiting the base of the organ with the lower rods turned on one side to

show the others, the shaded parts indicating {316}muscular attachments; B

is a transverse section of the organ. In these figures the different parts

of the appendages bear the same lettering as they do in Fig. 191. It will

be seen that in the completed structures the parts _c′_ have become very

intimately connected with the parts _b′_ and _b″_, which belong to another

segment.

The Locustidae resemble the Acridiidae in the possession of specialised

ears and sound-producing organs; neither of these is, however, situate in

the same part of the body as in Acridiidae. The ears of Locustidae are

placed on the front legs, below the knee; a tympanum (Fig. 193, A), or a

crack giving entrance to a cavity in which the tympanum is placed (Fig.

193, B), being seen on each side of each of the anterior pair of limbs. In

this family, as in the Acridiidae, three kinds of ear are recognised

according to the condition of the tympanum, which is either exposed (Fig.

193, A) or closed by an overgrowth of the integument (Fig. 193, B), or in a

condition to a certain extent different from either of these. The existence

of ears placed on the legs is a curious fact, but it is beyond doubt in the

Locustidae, and there is good reason for believing that analogous organs

exist in this situation in other Insects that have special means of

sound-production, such as the ants and the Termites.

[Illustration: FIG. 193.—Ears of Locustidae: A, portion of front leg of

_Odontura serricauda_, adult; _p_, prominence of integument; _r_, rim of

ear; _T_, tympanum; _b_, thickened area thereof; _Fu_, remains of groove in

which the structure was developed. B, portion of front leg of _Thamnotrizon

apterus_; _i_, inner margin; _a_, slit-like external aperture of ear; _di_,

overlapping cover of the ear. (After Graber.)]

The structure of these organs in the Locustidae has been investigated by

Graber,[247] and their acoustic functions placed beyond doubt, though to

what special kind of sounds they may be sensitive is not ascertained, this

point being surrounded by even greater difficulties than those we have

discussed in the case of the Acridiidae. In the Locustidae there is a

special structure of a remarkable nature in connexion with the ears. In

Acridiidae {317}a stigma is placed close to the ear, and supplies the

internal structures of the organ with air. There are no stigmata on the

legs of Insects, consequently admission of air to the acoustic apparatus in

Locustidae is effected by means of a gaping orifice at the back of the

prothorax, just over the base of the front leg (Fig. 101); this

communicates with its fellow of the other side, and from them there extend

processes along the femora into the tibiae, where they undergo dilatation,

so as to form vesicular cavities, one of which is in proximity to each drum

of the ear. These leg-tracheae are not connected with the ordinary tracheal

system; the prothoracic stigma exists in close proximity to the acoustic

orifice we have described, but is much smaller than it. It is not yet clear

why the acoustic apparatus should require a supply of air apart from that

which could be afforded by the ordinary tracheal system. This special

arrangement—to which there is hardly a parallel in Insect anatomy—has still

to be accounted for; we do not know whether the necessity for it may be

connected with the respiratory system or the acoustic organ.

[Illustration: FIG. 194.—Diagram of arrangement of parts of the ear as seen

in transverse section of the tibia of a Locustid. A, J, V, H, outer, inner,

anterior, posterior aspects of leg; _a_, _d_, thin part of integument

forming anterior tympanum; _b_, _c_, thicker portion of same; _f_, _g_,

posterior tympanum; _a_, _f_, and _d_, _h_, _g_, thick portions of

integument; _i_, _k_, internal protuberances of same; _l_, _m_, _n_, _o_,

walls of the anterior tracheal vesicle, _vTr_; _p_, _q_, _s_, _r_, walls of

the posterior tracheal vesicle, _hTr_; _o″_, projection of tympanal orifice

of prothorax; _tr-n_, tracheal nerve-end organ, _crista acustica_; _st_,

rod; _de_, curtain-membrane; _hn_, _e_, supra-tympanal, nerve-end organ;

_hn_, ganglion cells; _st′_, rods; _e_, point of integumental fixation of

nerve endings. (After Graber.)]

The chief features of the acoustic apparatus of the legs of Locustidae will

be gathered from the accompanying diagrammatic transverse section through

the tibia. In this figure the deep black parts indicate the outer wall of

the tibia and its prolongations, the white spaces indicate the parts filled

with air, while the dotted portions are occupied by blood or some of the

body organs;[248] the {318}circular space _o″_ is not part of the actual

structure, but represents the area of the external acoustic orifice of the

prothorax; it is not, however, so large as it should be.

Although the tibial ears of Locustidae are very perfect organs, there is

great difficulty in deciding on the exact nature of their functions. They

would appear to be admirably adapted to determine the precise locality from

which a sound proceeds, especially in those cases—and they are the highest

forms—in which the tympanum is placed in a cavity the external orifice of

which is a slit (Fig. 193, B); for the legs can be moved in the freest

manner in every direction, so as to bring the drum into the most direct

line of the vibrations. But as to what kinds of vibrations may be

perceived, and the manner in which they may be transmitted to the nerves,

there is but little evidence. On reference to the diagram it will be

noticed that the tympanum, the tympanal vesicles, and the nervous apparatus

are not in close connexion, so that even the mode by which the impulses are

transmitted is obscure.

The musical organs of the Locustidae are different from those of the

Acridiidae, and are invariably situate on the basal part of the tegmina.

They are found, in the great majority of cases, only in the male; in the

tribes Ephippigerides and Callimenides they exist in each sex. One of the

wings bears a file on its inner surface, while the other—on the right side

of the body—is provided with a sharp edge placed on a prominent part of its

inner margin. By slightly tilting the tegmina and vibrating them rapidly,

the edge passes under the file, and a musical sound is produced. These

structures are limited to the small anal area of the wing, and when the

tegmina are very greatly reduced in size, it is this part that still

remains. There is much variety in the details of the structure. The

nervures of this part of the tegmina are different in the male from what

they are in the female, and, moreover, the two wing-covers of the male

differ from one another. It is apparently the vibrations of the right

tegmen that produce the sound, and this part usually bears a space of a

glassy nature, which probably improves the character of the sound produced.

Our chief British songster of this group, _Locusta viridissima_, is only

provided with phonetic organs (Fig. 195) of a somewhat imperfect character,

but in the genus _Mecopoda_ there is great perfection of the structures.

The anal areas of the two tegmina are in this case {319}very different;

that of the left one, which bears the file, being similar in texture to the

rest of the wing-cover, while the corresponding part of the other tegmen is

rigid and transparent, and greatly distorted, so as to create a cavity

which, no doubt, improves the sound; the scraper too is very perfectly

formed. The difference between this form of musical organ and that of _L.

viridissima_ is curious, inasmuch as in the better instrument the important

modifications are confined to one tegmen, while in the other form both

tegmina are largely changed. The difference appears to be that in _Locusta_

the left tegmen, as well as the right one, acts as a sounding-board, while

in _Mecopoda_ it does not do so, but when the wings are closed quite covers

and conceals the musical instrument.

The Locustidae, notwithstanding the fact that their alar organs are

generally more ample than those of the Acridiidae, seem to be, as a rule,

of more sedentary habits, and more nocturnal in their activity. The musical

powers of the different species are very varied. _Locusta viridissima_

produces a shrill and monotonous but not disagreeable, sound, and is

capable of sustaining it for a quarter of an hour without any intermission,

except a break for the sake of starting again immediately with greater

force, like a performer on a flute. It occasionally chirps in the day, but

the act is then very brief. Bates informs us that one of these singing

grasshoppers, called Tananá by the natives of the Amazon valley, is much

admired for its singing, and is kept in little cages. The Amazonian

naturalist thought the music of this species superior to that of any other

Orthopterous Insect he had heard. The name of this grasshopper is

_Thliboscelus camellifolius_. It is very similar in appearance to

_Cyrtophyllus crepitans_, the Insect we have represented in Fig. 187.

[Illustration: FIG. 195.—Inner face of base of tegmina of _Locusta

viridissima_: A, the two wing-covers separated; B, in natural position with

mesonotum connecting them, showing file and edge scraping it; _a_, the

stridulating file; _b_, the rudimentary file on other tegmen.]

The most notorious of the musical Locustids are the Katydids {320}of North

America. There are several species of them—they belong, indeed, to more

than one genus,—but it seems that sounds somewhat resembling the words

Katy-did are perceptible in most of their performances. These sounds are

frequently repeated with slight variations—Katy-did, O-she-did,

Katy-did-she-did. Riley describes the music of the Katydid we represent in

Fig. 196 as follows:[249] "The first notes from this Katydid are heard

about the middle of July, and the species is in full song by the first of

August. The wing-covers are partially opened by a sudden jerk, and the

notes produced by the gradual closing of the same. The song consists of a

series of from twenty-five to thirty raspings, as of a stiff quill drawn

across a coarse file. There are about five of these raspings or trills per

second, all alike, and with equal intervals, except the last two or three,

which, with the closing of the wing-covers, run into each other. The whole

strongly recalls the slow turning of a child's wooden rattle, ending by a

sudden jerk of the same; and this prolonged rattling, which is peculiar to

the male, is invariably and instantly answered by a single sharp 'chirp' or

'tschick' from one or more females, who produce the sound by a sudden

upward jerk of the wings."

[Illustration: FIG. 196.—Katydid, _Microcentrum retinerve_. N. America.

(After Riley.)]

Pertinacity is one of the most curious features of the performance of

musical Locustids. One would say they desire to distinguish themselves as

much as possible. Harris says that _Cyrtophyllus concavus_ mounts on the

uppermost twigs of trees and there performs its Katy-did-she-did in rivalry

with others. He says even the female in this species gives forth a feeble

noise. Scudder says that some of the Katydids sing both by day and night,

but their day song differs from that of the night. "On a summer's day it is

curious to observe these little creatures suddenly {321}changing from the

day to the night song at the mere passing of a cloud, and returning to the

old note when the sky is clear. By imitating the two songs in the daytime

the grasshoppers can be made to respond to either at will; at night they

have but one note."

Although but little is known as to the habits of Locustidae, it is

ascertained that they are less exclusively herbivorous in their food habits

than the Acridiidae are; many seem to prefer a mixed diet. _Locusta

viridissima_ will eat various leaves and fruits, besides small quantities

of flesh. It has been recorded that a specimen in confinement mastered a

humble-bee, extracted with its mandibles the honey-bag, and ate this

dainty, leaving the other parts of the bee untouched. Many of the

Locustidae are believed to be entirely carnivorous. Brunner considers a

minority to be exclusively phytophagous. The species very rarely increase

to large numbers; this, however, occurs sometimes with _Orphania

denticauda_ and _Barbitistes yersini_ in Europe, and _Anabrus purpurascens_

in North America. We have already mentioned that the eggs of some species

are deposited in parts of plants, and of others in the earth. The British

_Meconema varium_ deposits its eggs in the galls of _Cynips_ in the autumn;

these eggs do not hatch till the following spring. _Xiphidium ensiferum_

has somewhat similar habits in North America, the gall selected for the

reception of the eggs being the scales formed by a species of _Cecidomyia_

on the leaves of willows. It has been ascertained that the development of

the embryo in the last-named species is commenced in the autumn, but is

suspended during the winter, being only completed in the following spring,

eight or nine months afterwards. We owe to Wheeler[250] a memoir on the

embryology of this Insect.

Some of the species have the peculiar habit of dwelling in caves. This is

especially the case with the members of the tribe Stenopelmatides (Fig.

197), which frequently possess enormously long antennae and legs, and are

destitute of alar organs and ears. The species with this habit, though

found in the most widely separated parts of the world, have a great general

resemblance, so that one would almost suppose the specimens found in the

caves of Austria, in the Mammoth cave of Kentucky, and in the rock-cavities

of New Zealand to be one {322}species, although they are now referred by

entomologists to different genera.

[Illustration: FIG. 197.—_Dolichopoda palpata_, male. Dalmatia. (After

Brunner.)]

[Illustration: FIG. 198.—Leaf-like tegmen of _Pterochroza ocellata_: _a_,

_a_, _a_, marks like those made by Insects on leaves.]

The Locustidae display in the greatest possible perfection that resemblance

of the tegmina to leaves which we mentioned when speaking of the general

characters of the Orthoptera. The wing-covers are very leaf-like in colour

and appearance in many Locustidae, but it is in the tribe Pseudophyllides

and in the South American genus _Pterochroza_ (Fig. 198) that the

phenomenon is most remarkable. The tegmina in the species of this genus

look exactly like leaves in certain stages of ripeness or decay. In the

tegmina of some of the species not only are the colours of faded leaves

exactly reproduced, but spots are present like those on leaves due to

cryptogamic growths. Perhaps the most remarkable feature of these

resemblances is the one pointed out by Brunner von Wattenwyl,[251] viz.

that the tracks and spots formed on leaves by the mining of Insects in

their tissues are also represented in the leaf-like wing-covers of the

_Pterochroza_; transparent spots (_a_, _a_, Fig. 198) being present, just

as they are in many leaves that have been attacked by Insects. Brunner was

so much impressed by these facts that he came to the conclusion that they

cannot be accounted for on the grounds of mere utility, {323}and proposed

the term Hypertely to express the idea that in these cases the bounds of

the useful are transcended. We will mention here another peculiar case of

resemblance described by Brunner as occurring in a Locustid. Two specimens

of a little Phaneropterid were brought from the Soudan by the Antinori

expedition, and have been described by Brunner under the name of

_Myrmecophana fallax_. The Insect is said to bear an extraordinary

resemblance to an ant. The most peculiar feature in the resemblance is

shown in Fig. 199, A, B. The most characteristic point in the external form

of an ant is the stalked abdomen, this structure being at the same time

quite foreign to the Orthoptera. In the other parts of the body and in the

colour generally, the _Myrmecophana_ resembles an ant, but the abdomen of

the Orthopteron is not stalked; it has, however, the appearance of being

so, in consequence of certain parts being of a white colour, as shown in

our figure. If abstraction be made of the white parts, the form of the

stalked abdomen of the ant is nicely reproduced. The specimens brought from

the Soudan were wingless and destitute of ovipositor, and may be immature,

but Brunner suggests that they may prove to be really mature, the

ovipositor, tegmina, and wings being permanently absent. The existence of a

long ovipositor would certainly detract greatly from the ant-like

appearance of the Orthopteron.

[Illustration: FIG. 199.—_Myrmecophana fallax._]

It is certain that the plant-like appearance of some of the Locustidae

renders them inconspicuous to the human eye in the situations they

frequent. It is a matter of common observation that though the noise of

their chirpings may be heard to such an extent as to make it certain that

many individuals must be in the immediate neighbourhood, yet at the same

time it may be most difficult to detect even a single individual. M. Boutan

noticed this phenomenon in the case of _Ephippigera rugosicollis_, and

tells us that the human eye can, with a little practice, acquire the art of

detecting these concealed creatures. This consists {324}apparently in

making use, not of a general inspection, but of a scrutiny of the outlines

of the leaves and twigs of a tree. By this means, when the eye is

accustomed to the task, the Insects can be detected with comparative ease;

much in the same way, M. Boutan says, as a figure, placed in an engraving

in such a way as to elude the eye, is appreciated with ease after the eye

has once perceived it.

Some of the Locustidae are provided with means of defence of a positive

nature. The Algerian _Eugaster guyoni_ ejects two jets of a caustic

orange-coloured fluid from two pores situate on the sides of the

mesosternum, and covered by the anterior coxae. This species is carnivorous

as well as herbivorous, and produces a sound more like humming than

stridulation.[252]

[Illustration: FIG. 200.—_Phasmodes ranatriformis_,female. Australia.

(After Westwood.)]

We have previously pointed out that some of the Acridiidae resemble the

stick-Insects rather than the members of their own group; and similar cases

occur amongst the Locustidae. Such a resemblance has, however, only been

found in a few species of the tribe Prochilides. We figure one of these,

_Phasmodes ranatriformis_, a native of South-West Australia. The very

elongate linear form and the total absence of alar organs give this Insect

a considerable resemblance to the stick-Insects or apterous Phasmidae.

_Prochilus australis_ is allied to this curious Locustid, but the alar

organs are present in both sexes, and the Insect bears a great resemblance

to the winged Phasmidae. This is due not only to the general form and

colour, but also to the fact that the tegmina are very narrow, which

{325}causes them to look like the coloured slip on the anterior parts of

the wings of some of the Phasmidae (cf. p. 266). Another case of a Locustid

with elongate, slender form is found in the extraordinary _Peringueyella

jocosa_ of South Africa, a member of the tribe Sagides. It has minute

organs of flight, and reproduces, to a considerable extent, the form and

appearance of Proscopides or of some Tryxalides.[253]

[Illustration: FIG. 201.—_Schizodactylus monstrosus_, male. Natural size.

East India.]

We follow Brunner in placing among the Locustidae the large Insect we

represent in Fig. 201. It is remarkable on account of its tegmina and

wings; these have their extremities much prolonged and curled; moreover,

the flat interior area and the abruptly {326}deflexed exterior area make

them look more like the wings of Gryllidae. This species has no ocelli, and

is said to be destitute of ears. The inflated condition of the anterior and

middle tibiae suggest that it possesses auditory structures, though there

appears to be no external opening for them. This Insect is found in India,

where it is said to be common on the banks of sandy rivers, living there in

burrows of the depth of three feet. Very little is known, however, as to

this curious Insect. It has recently been reported[254] as being injurious

to tobacco and other crops on high ground in Durbungha by cutting off their

roots. The local name for the Insect is _bherwa_. We should think it

somewhat doubtful whether this refers really to _S. monstrosus_.

[Illustration: FIG. 202.—_Anostostoma australasiae_, male. Australia.]

In number of species the Locustidae are perhaps scarcely inferior to the

Acridiidae, and in variety of form they surpass this latter family. Many of

the most gigantic forms are apterous, and these very often have a repellant

aspect. The genus _Anostostoma_ is remarkable for its large head. Allied to

it is _Deinacrida heteracantha_, the "Weta-punga" of the New Zealand

natives, an Insect formerly abundant in the forests north of Auckland, but

of late years become extremely rare. The head and body of this Insect may

measure more than 2½ inches in length, and when the antennae and legs are

stretched out the total length may be 14 or 15 inches. Although bulky and

absolutely wingless, yet, as Buller informs us,[255] it climbs with

agility, and is sometimes found on the topmost branches of lofty trees.

When disturbed it produces a clicking, accompanied by a slow movement

{327}of its hind legs. A second species, _D. thoracica_, lives in decayed

wood, and a third, _D. megacephala_, is remarkable from the very large size

of the head and mandibles in the male sex. The fact that a clicking noise

is produced by the Weta-punga is of some interest, for the genus

_Deinacrida_ is among the Locustidae that possess ears, but are said to be

destitute of sound-producing organs.

Amongst the most remarkable of the Locustidae are the two species of which

Brongniart has recently formed the genus _Eumegalodon_ and the tribe

Eumegalodonidae, which is not included in Brunner's table of the tribes of

Locustidae. The ovipositor is large and sabre-shaped; the male is unknown.

The genus _Megalodon_ is placed by Brunner in the tribe Conocephalides; it

also consists of extremely remarkable Insects.

[Illustration: FIG. 203.—_Eumegalodon blanchardi_, female. Borneo. × ⅘.

(After Brongniart.)]

The Locustidae appear to be of slow growth, and the autumns of Britain are

usually not warm enough for them. Hence we have but nine British species,

and of this number only three or four are known to occur north of the

Thames. The only one that attracts attention is _Locusta viridissima_,

which in some districts of the south of England occurs in considerable

numbers, and attests its presence by its peculiar music. It is called the

green grasshopper.

{328}The geological record is rather obscure in the matter of Locustidae.

Scudder considers that a fair number of Tertiary forms are known, and says

that they represent several of the existing tribes and genera. One or two

have been found in Mesozoic rocks.

TABLE OF THE TRIBES OF LOCUSTIDAE

1. Tarsi more or less depressed.

2. Front tibiae furnished with auditory cavities.

3. Antennae less distant from the summit of the occiput than from the

labrum; inserted between the eyes.[256]

4. First two joints of the tarsi laterally smooth. (Posterior

tibiae furnished on each side with an apical spine.) Tribe 1.

PHANEROPTERIDES. (Fig. 196, _Microcentrum_; Fig. 199,

_Myrmecophana_. Fig. 101, _Poecilimon affinis_.)

4′. First two joints of the tarsi laterally, longitudinally

sulcate.

5. Foramina of the anterior tibiae normally open. (Fig. 193, A.)

6. Posterior tibiae furnished on each side with apical spines.

7. Prosternum unarmed. Tribe 2. MECONEMIDES.

7′. Prosternum bispinose or bituberculate. Tribe 3.

MECOPODIDES.

6′. Posterior tibiae with no apical spines. (Head prognathous.)

Tribe 4. PROCHILIDES. (Fig. 200, _Phasmodes_.)

5′. Foramina of the anterior tibiae forming a chink, or protected

by a scale. (Fig. 193, B.)

6. Anterior tibiae with no apical spines.

7. Margins of the scrobes[257] of the antennae prominent.

Tribe 5. PSEUDOPHYLLIDES. (Fig. 187, _Cyrtophyllus

crepitans_; Fig. 198, _Pterochroza ocellata_.)

7′. Margins of the scrobes of the antennae not prominent.

8. Posterior tibiae furnished above on each side with

apical spines, or with a single spine on the side.

9. Posterior tibiae either furnished with apical spines

on each side, or only on the inner side. Tribe 6.

CONOCEPHALIDES. (Fig. 189, _Copiophora cornuta_.)

9′. Posterior tibiae furnished above with an apical spine

placed only on the outer side. Tribe 7. TYMPANOPHORIDES.

8′. Posterior tibiae without apical spines. Tribe 8.

SAGIDES.

6′. Anterior tibiae furnished with an apical spine on the inner

side.[258]

{329}7. The first joint of the posterior tarsi destitute of a

free sole-lobe. Tribe 9. LOCUSTIDES.

7′. The first joint of the posterior tarsi furnished with a

free sole-lobe. Tribe 10. DECTICIDES.

3′. Antennae more distant from the summit of the occiput than from

the labrum, inserted either beneath the eyes or on their inferior

border. Tegmina and wings greatly abbreviate, scale-like; when

tegmina are present they are furnished in each sex with a tympanum.

4. Third joint of the posterior tarsi shorter than the second. Both

anterior and posterior tibiae furnished on each side with a spine.

Tribe 11. CALLIMENIDES.

4′. Third joint of posterior tarsi longer than the second joint.

Anterior tibiae with no apical spine on the inner side, and

posterior tibiae with no apical spine on the outer side.

5. Antennae inserted at the edge of the eyes. Pronotum unarmed.

Tegmina present in each sex. Anterior tibiae furnished on the

outer side with an apical spine. Posterior tibiae furnished

beneath with four apical spines. Tribe 12. EPHIPPIGERIDES.

5′. Antennae inserted distinctly below the eyes. Pronotum

spinous. Elytra in the females wanting. Anterior tibiae without

apical spine on either side. Posterior tibiae beneath with two

apical spines or with none. Tribe 13. HETRODIDES.

2′. Anterior tibiae without auditory cavities. Tegmina with no

tympanum. Tribe 14. GRYLLACRIDES. (Fig. 201, _Schizodactylus

monstrosus_.)

1′. Tarsi distinctly compressed (most of the species apterous.) Tribe 15.

STENOPELMATIDES. (Fig. 202, _Anostostoma australasiae_; Fig. 197,

_Dolichopoda palpata_.)

{330}CHAPTER XIV

ORTHOPTERA _CONTINUED_—GRYLLIDAE, CRICKETS

FAM. VIII. GRYLLIDAE—CRICKETS.

_Antennae very slender, generally long and setaceous; hind legs long,

saltatorial. Tegmina with the outer portion deflexed on to the side of

the body, and with the inner part lying flat on the body. Tarsi usually

three-jointed (rarely two- or four-jointed). Female with a long

ovipositor (except in Gryllotalpides). Apterous forms numerous._

The Gryllidae are closely connected with the Locustidae, the musical and

auditory organs being in both similarly situate, and the female in both

possessing, in most of the tribes, an elongate exserted ovipositor. The two

families differ in the number of joints of the tarsi, in the form of the

tegmina, and in the fact that in Gryllidae the portion of the wing modified

for musical purposes consists of a larger portion of the organ—according to

de Saussure, the discoidal as well as the anal area.

[Illustration: FIG. 204.—House-cricket, _Gryllus_ (_Acheta_) _domesticus_,

male.]

The family would be a very natural one if we were to exclude from it the

mole-crickets which have fossorial front legs and no ovipositor, and the

Tridactylides, which also are {331}destitute of ovipositor, and have short

antennae, consisting of about ten joints.

The head is generally very large; ocelli are present, though usually

imperfect; the extremity of the body bears a pair of remarkably long cerci.

The hind tibiae are usually armed with very strong spines; the first joint

of the hind tarsus is elongate, and terminates in two spines, between which

the small second joint is often almost completely concealed; the feet are

not provided beneath with pads, but only bear remote setae.

The alar organs are difficult of comprehension, and different opinions

prevail as to their morphology. The tegmina are extremely different to the

hind wings, and never attain large dimensions, neither do they exhibit any

leaf-like or ornamental structures. In the genus _Pteroplistus_ they are

formed somewhat like the elytra of Coleoptera, and close over the back of

the Insect in a fashion very like that found in beetles. According to

Brunner the larger part of the tegmen—which, as we have said, reposes flat

on the back of the Insect—represents merely the anal area, and all the

other parts must be sought in the smaller, deflexed portion of the

wing-cover. De Saussure's opinion, to a somewhat different effect, we have

already mentioned. The tegmina of the male are extremely different from

those of the female, so that it is a matter of much difficulty to decide

what nervures correspond.[259]

[Illustration: FIG. 205.—Tegmina (sinistral) of the house-cricket. A, male,

inner aspect; B, female, outer aspect: _a_, inner margin; _b_, outer

margin; _c_, nervure bearing stridulating file.]

The wing-covers of the male differ from those of the Locustidae, inasmuch

as the pair are of similar formation, each bearing a stridulating file on

its lower aspect. This file projects somewhat inwards, so that its position

is marked on the outer aspect of the wing-cover by a depression. Usually

the right tegmen overlaps the other, an arrangement contrary to that which

prevails in other Orthoptera. The wings are ample and delicate; they

possess numerous nervures that are not much forked and have a {332}simple,

somewhat fan-like arrangement; the little transverse nervules exhibit only

slight variety. These wings are frequently rolled up at the apex, and

project beyond the body like an additional pair of cerci (Fig. 204). The

abdomen is chiefly remarkable for the large development of the pleura, the

stigmata being consequently very conspicuous. The cerci are not jointed,

though they are flexible and, often, very long; they bear a variety of

sense-organs (Fig. 67). The saltatorial powers of the crickets are

frequently considerable.

Graber has observed the post-embryonic development of the field-cricket,

_Gryllus campestris_, though unfortunately not from the very commencement,

so that we do not know whether there are five, six, or seven ecdyses; the

number is probably either six or seven. The manner in which the alar organs

are developed is similar to that we have described and figured in the

Locustidae. In the earlier instars there is a slight prolongation of each

side of the meso- and meta-notum, but about the middle of the development a

considerable change occurs—the rudimentary organs then become free

appendages and assume a different position.

The Gryllidae possess a pair of tympana on each front leg, but these organs

contrast with those of the Locustidae in that the pair on each leg usually

differ from one another, the one on the outer or posterior aspect being

larger than that on the inner or front face of the leg.

The ears of the Gryllidae have not been so well investigated as those of

the Locustidae, but are apparently of a much less perfect nature. No

orifice for the admission of air other than that of the prothoracic stigma

has been detected, except in _Gryllotalpa_. On the other hand, it is

said[260] that in addition to the tibial organs another pair of tympana

exists, and is seated on the second abdominal segment in a position

analogous to that occupied by the ear on the first segment of Acridiidae.

The musical powers of the crickets are remarkable, and are familiar to all

in Europe, as the performance of the house-cricket gives a fair idea of

them. Some of the Insects of the family are able to make a very piercing

noise, the note of _Brachytrypes megacephalus_ having been heard, it is

said, at a distance of a mile from where it was being produced. The mode of

{333}production is the same as in the Locustidae, rapid vibration of the

tegmina causing the edge of one of them to act on the file of the other.

The mole-cricket, _Gryllotalpa vulgaris_—the _Werre_ of the Germans,

_Courtilière_ of the French—is placed with a few allies in a special group,

Gryllotalpides, characterised by the dilated front legs, which are

admirably adapted for working underground. Like the mole, this Insect has a

subterranean existence. It travels in burrows of its own formation, and it

also forms beneath the surface a habitation for its eggs and family. Its

habits have been alluded to by Gilbert White,[261] who tells us that "a

gardener at a house where I was on a visit, happening to be mowing, on the

6th of May, by the side of a canal, his scythe struck too deep, pared off a

large piece of turf, and laid open to view a curious scene of domestic

economy: there were many caverns and winding passages leading to a kind of

chamber, neatly smoothed and rounded, and about the size of a moderate

snuff-box. Within this secret nursery were deposited near a hundred eggs of

a dirty yellow colour, and enveloped in a tough skin, but too lately

excluded to contain any rudiments of young, being full of a viscous

substance. The eggs lay but shallow, and within the influence of the sun,

just under a little heap of fresh moved mould like that which is raised by

ants."

[Illustration: FIG. 206.—Front leg of the mole-cricket. A, outer; B, inner

aspect: _e_, ear-slit.]

The front legs are remarkable structures (Fig. 206), being beautifully

adapted for burrowing; the tibiae and tarsi are arranged so as to act as

shears when it may be necessary to sever a root. The shear-like action of

the tarsus and tibia is very remarkable; the first and second joints of the

former are furnished with hard processes, which, when the tarsus is moved,

pass over the edges of the tibial teeth in such a way as to be more

effective than a pair of shears. In consequence of its habit of cutting

roots, {334}the mole-cricket causes some damage where it is abundant. It is

now a rare Insect in England, and is almost confined to the southern

counties, but in the gardens of Central and Southern Europe it is very

abundant. Its French name _courtilière_ is supposed to be a corruption of

the Latin _curtilla_. Its fondness for the neighbourhood of water is well

known. De Saussure says that in order to secure specimens it is only

necessary to throw water on the paths between the flower-beds of gardens

and to cover the wetted places with pieces of board; in the morning some of

these Insects are almost sure to be found under the boards disporting

themselves in the mud. The Gryllotalpae swim admirably by aid of their

broad front legs.

Ears exist in the mole-cricket, and are situate on the front leg below the

knee, as in other Gryllidae, although it seems strange that a leg so

profoundly modified for digging and excavating as is that of the

mole-cricket should be provided with an ear. In _Gryllotalpa_ the ear is

concealed and protected by being placed in a deep slit or fold of the

surface, and this depression is all that can be seen by examination of the

exterior (Fig. 206, _e_). In the allied genus _Scapteriscus_ the tympanal

membrane is, however, destitute of special protection, being completely

exposed on the surface of the leg.

Although the tegmina or upper wings in _Gryllotalpa_ are of small size, yet

the true wings are much more ample; they are of delicate texture and

traversed by many nearly straight radii, so that they close up in the most

complete manner, and form the two long delicate, flexible processes that in

the state of repose may be seen projecting not only beyond the tegmina, but

actually surpassing the extremity of the body hanging down behind it, and

looking like a second pair of cerci.

The mole-cricket is believed to be chiefly carnivorous in its diet, though,

like many other Orthoptera, it can accommodate its appetite to parts of the

vegetable as well as of the animal kingdom. The Insect is capable of

emitting a sound consisting of a dull jarring note, somewhat like that of

the goat-sucker. For this purpose the tegmina of the males are provided

with an apparatus of the nature we have already described, but which is

very much smaller and less elaborate than it is in the true crickets.

{335}[Illustration: FIG. 207.—Alimentary canal and appendages of the

mole-cricket: _a_, head; _b_, salivary glands and receptacle; _c_, lateral

pouch; _d_, stomato-gastric nerves; _e_, anterior lobes of stomach; _f_,

peculiar organ; _g_, neck of stomach; _h_, plicate portion of same; _i_,

rectum; _k_, lobulate gland; _l_, extremity of body; _m_, Malpighian tubes.

(After Dufour.)]

The alimentary canal and digestive system of _Gryllotalpa_ present

peculiarities worthy of notice. Salivary glands and reservoirs are present;

the oesophagus is elongate, and has on one side a peculiar large pouch

(Fig. 207, _c_); beyond this is the gizzard, which is embraced by two lobes

of the stomach. This latter organ is, beyond the lobes, continued backwards

as a neck, which subsequently becomes larger and rugose-plicate. On the

neck of the stomach there is a pair of branching organs, which Dufour

considered to be peculiar to the mole-cricket, and compared to a spleen or

pancreas. The single tube into which the Malpighian tubules open is seated

near the commencement of the small intestine. These tubules are very fine,

and are about one hundred in number. The arrangement by which the

Malpighian tubules open into a common duct instead of into the intestine

itself appears to be characteristic of the Gryllidae, but is said to occur

also in _Ephippigera_, a genus of Locustidae. According to Leydig[262] and

Schindler the Malpighian tubules are of two kinds, differing in colour,

and, according to Leydig, in contents and histological structure. Near the

posterior extremity of the rectum there is a lobulated gland having a

reservoir connected with it; this is the chief source of the foetid

secretion the mole-cricket emits when seized. The nervous chain consists of

three thoracic and four abdominal ganglia; these latter do not extend to

the extremity of the body; {336}the three anterior of the four ganglia are

but small, the terminal one being much larger.

The number of eggs deposited by a female mole-cricket is large, varying, it

is said, from 200 to 400. The mother watches over them carefully, and when

they are hatched, which occurs in a period of from three to four weeks

after their deposition, she supplies the young with food till their first

moult; after this occurs they disperse, and begin to form burrows for

themselves.

It has been said that the young are devoured by their parents, and some

writers have gone so far as to say that 90 per cent of the progeny are thus

disposed of. M. Decaux, who has paid considerable attention to the economy

of the mole-cricket,[263] acquits the mother of such an offence, but admits

that the male commits it. The number of eggs in one nest is said to be

about 300.

The embryonic development of the mole-cricket has been studied by

Dohrn[264] and Korotneff,[265] and is considered by the former to be of

great interest. The tracheae connected with each stigma remain isolated,

while, according to Korotneff, the development of the alimentary canal is

not completed when the young mole-cricket is hatched. Perhaps it may be

this condition of the digestive organs that necessitates the unusual care

the mother bestows on her young.

[Illustration: FIG. 208.—_Cylindrodes kochi._ Australia. A, outline of the

Insect with five of the legs and the extremity of the body mutilated; B,

middle leg. (After de Saussure.)]

The genus _Cylindrodes_ (Fig. 208, _C. kochi_) comprises some curious and

rare Insects of elongate, slender form. They are natives of Australia,

where the first species known of the genus was found in Melville Island by

Major Campbell, from whom we learn that these Insects burrow in the stems

of plants, and are so destructive that he was unable to keep a single plant

in his greenhouse on account of the ravages of _Cylindrodes campbellii_.

The form of these Insects is beautifully adapted to {337}their habits, the

body being contracted in the middle in such a way as to permit the middle

and hind legs to be packed against it, so that the cylindrical form is not

interfered with by these appendages while the excavating anterior legs are

at work in front of the Insect. The abdomen has nine segments; the terminal

one, said to be remarkably long and destitute of cerci, is not shown in our

figure.

The genus _Tridactylus_ is considered by de Saussure to form, with its ally

_Rhipipteryx_, a division of Gryllotalpinae, but they are treated, perhaps

more correctly, by Brunner as a separate tribe. _T. variegatus_ (Fig. 209)

is a small Insect, abundant in sandy places on the banks of rivers in

Southern Europe,—extending on the Rhone as far north as Geneva,—and is

remarkable for its great power of leaping, and for the rapidity with which

it can burrow in the sand. This anomalous Insect has only ten joints to the

antennae. Its alar organs are imperfect, and not like those of other

Gryllidae in either form or neuration. The hind legs are of peculiar

structure, the tibiae terminating in two processes between which is situate

a rudimentary tarsus. Near the extremity of the tibia there are some

plates, forming two series, that can be adpressed to the tibia, or extended

as shown in our figure. The body is terminated by four rather short, very

mobile processes; the upper pair of these are each two-jointed, and are

thought by de Saussure and Haase[266] to be cerci; the inferior pair, being

articulated processes of the anal segment, their presence in addition to

cerci is remarkable. It is difficult to distinguish the sexes of this

Insect.

[Illustration: FIG. 209.—_Tridactylus variegatus_, France.]

The exotic genus _Rhipipteryx_ is allied to _Tridactylus_. It is widely

distributed in South America, but the little Insects that {338}compose it

are rare in collections, their saltatorial powers no doubt making it

difficult to catch them; little is known as to their habits. In the

undescribed Amazonian species we figure (Fig. 210), the wings, instead of

being mere rudiments, as in _Tridactylus_, are elongate and project beyond

the body; they are of a blue-black colour, and arranged so as to look as if

they were the abdomen of the Insect; they, moreover, have a transverse

pallid mark, giving rise to an appearance of division. It is difficult to

form any surmise as to the nature of so curious a modification of the

wings.

The Tridactylides have no tympana on the legs, and their affinity with the

Gryllidae is very doubtful. Dufour thought _T. variegatus_ to be more

allied to the Acridiidae. He based this opinion chiefly on some points of

the internal anatomy, but pointed out that _Tridactylus_ differs from the

Acridiidae in having no air-sacs in the body.

[Illustration: FIG. 210.—_Rhipipteryx_ sp., Amazon valley.]

Not many of the Gryllidae are so peculiar as the forms we have mentioned.

The family consists in larger part of Insects more or less similar to the

common cricket, though exhibiting a great variety of external form. The

common cricket of our houses, _Gryllus (Acheta) domesticus_ (Fig. 204), has

a very wide distribution in the Old World, and is also found in North

America. It is believed to have had its natural distribution extended by

commerce, though really nothing is known as to its original habitat. The

shrill chirping of this little Insect is frequently heard at night in

houses, even in the most densely inhabited parts of great cities. Neither

the female nor the young are musical, yet the chirping may be heard at all

seasons of the year, as young and adults coexist independent of season. The

predilection of _Gryllus domesticus_ for the habitations of man is very

curious. The Insect is occasionally found out of doors in the neighbourhood

of dwelling-houses in hot weather, but it does not appear that this species

leads anywhere a truly wild life. It is fond of heat; though it rarely

multiplies in dwelling-houses to any great extent, it is sometimes found in

profusion in {339}bake-houses. Usually the wings in the cricket are

elongate, and project backwards from under the tegmina like an additional

pair of cerci; a variety, however, occurs in which these tails are absent,

owing to abbreviation of the wings.

There is no beauty in the appearance of any of the Gryllidae, though many

of them are very bizarre in shape. Very few of them venture to leave the

surface of the earth to climb on plants. The species of _Oecanthus_,

however, do so, and may be found sitting in flowers. They have a more

Locustoid appearance than other Gryllidae. One of the most curious forms of

the family is _Platyblemmus_, a genus of several species found in the

Mediterranean region, the male of which has the head prolonged into a

curious process (Fig. 211); this varies greatly in development in the males

of the same species. It would seem that this organ is of a similar nature

to the extraordinary structures we have figured in Locustidae (Fig. 189)

and Mantidae (Fig. 136), though it appears impossible to treat the cephalic

appendages of _Platyblemmus_ as ornamental objects; their import is at

present quite obscure.

A curious form of variation occurs in this family, and is called

micropterism by de Saussure; we have already mentioned its occurrence in

the house-cricket. The hind wings, which are usually ample, and frequently

have their extremities rolled up and protruding like cerci, are sometimes

much smaller in size, and not visible till the tegmina are expanded. De

Saussure at one time supposed these micropterous individuals to be distinct

species; it is now, however, known that intermediate examples can be found

by examining a great many specimens. Some species are always micropterous.

[Illustration: FIG. 211.—_Platyblemmus lusitanicus_, male. A, front of

head; B, profile of Insect with most of the appendages removed.]

In Britain we have only four representatives of the Gryllidae, viz. the

mole-cricket, the house-cricket, and two field-crickets, one of which,

_Nemobius sylvestris_, is considerably smaller than the house-cricket,

while the other, _Gryllus campestris_, the true field-cricket, is a larger

Insect. Its habits have been described in an interesting manner in Gilbert

White's 88th letter. {340}This Insect, like so many others, is apparently

becoming rare in this country.

A single fossil from the Lias has been described as belonging to the

Gryllidae, but in the Tertiary strata a variety of members of the family

have been discovered both in Europe and North America.

The classification of Gryllidae is due to de Saussure,[267] and is said by

Brunner to be very natural. In the following synopsis of the tribes of

crickets we give de Saussure's arrangement, except that we follow Brunner

in treating Tridactylides as a distinct tribe:—

1. Antennae ten-jointed; posterior tarsi aborted. Tribe 1. TRIDACTYLIDES.

(Fig. 209, _Tridactylus variegatus_; Fig. 210, _Rhipipteryx_ sp.)

1′. Antennae many jointed; posterior tarsi normal.

2. Tarsi compressed, the second joint minute.

3. Anterior legs fossorial; anterior tibiae at the apex with two to

four divisions. Pronotum elongate, ovate, rounded behind. Female

without ovipositor. Tribe 2. GRYLLOTALPIDES. (Fig. 206, front legs of

_Gryllotalpa_; Fig. 208, _Cylindrodes kochi_.)

3′. Anterior legs formed for walking. Ovipositor of the female

visible (either elongate or rudimentary).

4. Posterior tibiae biseriately serrate. Tribe 3. MYRMECOPHILIDES.

4′. Posterior tibiae biseriately spinose. Ovipositor straight.

5. Antennae short, thickish, almost thread-like. Facial

scutellum exserted between antennae. Posterior tibiae dilated.

Gen. _Myrmecophila_.[268]

5′. Antennae elongate, setaceous. Facial scutellum transverse,

visible below the antennae. Tibiae slender.

6. Posterior tibiae armed with two strong spines, not serrate

between the spines. Tribe 4. GRYLLIDES. (Fig. 204, _Gryllus

domesticus_; Fig. 211, _Platyblemmus lusitanicus_.)

6′. Posterior tibiae slender, armed with slender spines, and

serrate between them. Tribe 5. OECANTHIDES.

2′. Second joint of the tarsi depressed, heart-shaped.

3. Posterior tibiae not serrate, but biseriately spinose.

4. The spines on each side three and mobile; apical spurs on the

inner side only two in number. Ovipositor short, curved. Tribe 6.

TRIGONIDIIDES.

4′. The spines numerous, fixed. Ovipositor elongate, straight. Gen.

_Stenogryllus_.

3′. Posterior tibiae serrate and spinose on each side, the apical

spurs, as usual, three on each side. Ovipositor straight or curved.

Tribe 7. ENEOPTERIDES.

{341}CHAPTER XV

NEUROPTERA—MALLOPHAGA—EMBIIDAE

ORDER III. NEUROPTERA.

_Imago with biting mouth; with two pairs of wings, the anterior as well as

the posterior membranous, usually with extensive neuration, consisting of

elongate nervures and either of short cross-nervules forming numerous cells

or of a complex minute mesh-work. (One division, Mallophaga, consists

entirely of wingless forms; in Termitidae some of the individuals of each

generation become winged, but others do not: except in these cases adult

wingless forms are few.) The metamorphosis differs in the several

divisions._

[Illustration: FIG. 212.—_Osmylus chrysops_, New Forest.]

The Neuroptera form a heterogeneous, though comparatively small, Order of

Insects, including termites, stone-flies, dragon-flies, may-flies,

caddis-flies, lace-wings, scorpion-flies, ant-lions, etc. Bird-lice are

also included in Neuroptera, though they have no trace of wings.

We treat the Order as composed of eleven distinct families, {342}and, as a

matter of convenience, arrange them in five divisions:—

1. _Mallophaga_.—Permanently wingless Insects, living on the bodies of

birds or mammals. (Development very imperfectly known.) Fam. 1.

Mallophaga.

2. _Pseudoneuroptera_.—Insects with wings in adult life (in some cases

wings are never acquired). The wings are developed in a visible manner

outside the body. There is no definite pupa. Live entirely on land. Fam.

2. Embiidae; 3. Termitidae; 4. Psocidae.

3. _Neuroptera amphibiotica_.—Wings developed as in division 2. Three

ocelli usually exist. Life aquatic in the early stages. Fam. 5. Perlidae;

6. Odonata; 7. Ephemeridae.

4. _Neuroptera planipennia_.—Wings developed internally; not visible in

early stages, but becoming suddenly evident when the pupal form is

assumed. Mandibles present in the adult Insect. Life in early stages

aquatic or terrestrial. Fam. 8. Sialidae; 9. Panorpidae; 10.

Hemerobiidae.

5. _Trichoptera_.—Development as in division 4. Mandibles absent in the

adult Insect. Life aquatic in the early stages. Fam. 11. Phryganeidae.

The families we have enumerated in the preceding scheme are now generally

adopted by entomologists. Great difference of opinion exists, however, as

to the groups of greater value than the family, and for a long time past

various schemes have been in vogue. Though it is necessary to allude to the

more important of these systems, we can do so only in the briefest manner.

Some of the families of Neuroptera are similar in many points of structure

and development to Insects of other Orders; thus Termitidae are somewhat

allied to Blattidae, Perlidae to Phasmidae in Orthoptera, while the

Phryganeidae or Trichoptera make a considerable approach to Lepidoptera.

Some naturalists—among whom we may mention Burmeister and Grassi—unite our

Aptera, Orthoptera, and most of our Neuroptera into a single Order called

Orthoptera. Others treat our Neuroptera as consisting of eight or nine

distinct Orders; these, together with the names proposed for them, we have

already alluded to in our chapter on classification, pp. 171-177.

Erichson, impressed by the variety existing in Neuroptera, separated some

of the groups into a sub-Order called Pseudoneuroptera; this sub-Order

comprised our Termitidae, Psocidae, Ephemeridae, and Libellulidae. This

division is still adopted in several treatises; the Pseudoneuroptera are

indeed by some naturalists retained as an Order distinct from both

Orthoptera {343}and Neuroptera. Gerstaecker subsequently made use of a

system somewhat different from that of Erichson, uniting the Perlidae,

Ephemeridae, and Odonata into a group called _Orthoptera amphibiotica_,

from which the Termitidae and Psocidae were excluded. The divisions we have

here adopted differ but little from those of Gerstaecker, though we have

arranged them in a very different manner. It is probable that not one-tenth

part of the Neuroptera existing in the world have yet been examined by

entomologists, and of those that are extant in collections, the

life-histories and development are very imperfectly known. We have,

therefore, not considered it wise to adopt a system that would involve

great changes of nomenclature, while there can be little hope of its

permanency.

FOSSILS.—When considering the subject of fossil Insects we briefly alluded

to the discussions that have occurred as to whether the fossils of the

palaeozoic period should be referred to existing Orders. Since the pages we

allude to were printed, M. Brongniart's very important work[269] on the

Insects of that epoch has appeared. He considers that these ancient fossils

may be classified with the existing Orders of Insects, though they cannot

be placed in existing families; and he assigns the palaeozoic fossil

Insects at present known, to the Orders Neuroptera and Orthoptera, and to

the homopterous division of Hemiptera. The greater part of the species he

looks on as Neuroptera, and places in six families—Megasecopterides,

Protephemerides, Platypterides, Stenodictyopterides, Protodonates, and

Protoperlides. Of these he considers the ancient Protephemerides,

Protodonates, and Protoperlides as the precursors, which, we presume, we

may interpret as the actual ancestors, of our existing Ephemeridae,

Odonata, and Perlidae.

Some of the fossils restored and described by the French entomologist are

of great interest. We shall notice the Protephemerides, Protodonates, and

Protoperlides in connexion with the families to which they are specially

allied, and shall now only allude to the quite extinct families of

Neuroptera, the Megasecopterides, Platypterides, and Stenodictyopterides.

It is a peculiarity of these ancient Insects that they were much larger

creatures than the corresponding forms that now exist. This may be due, to

some extent, to the fact that tiny, {344}fragile forms have not been

preserved in the rocks, or have not attracted the attention of collectors;

but as some of the palaeozoic Insects were absolutely the largest

known—surpassing considerably in size any Insects at present existing—it is

probable that, even if small forms existed at the remote epoch we are

alluding to, the average size of the individual was greater than it is at

present. The Megasecopterides of the carboniferous epoch were Insects of

large size, with long, narrow wings, a small prothorax, and large meso- and

meta-thorax, these two segments being equal in size; the abdomen was

elongate and moderately voluminous, and was terminated by a pair of very

elongate, slender filaments like those of the may-flies. The family

includes several genera and species found at Commentry. One of these forms,

_Corydaloides scudderi_, is of great interest, as it is believed by

Brongniart that the imago possessed tracheal gills situated on the sides of

the abdomen, analogous with those that exist at present in the immature

condition of certain Ephemeridae. They are of interest in connexion with

the gills found at the present time in the imagos of _Pteronarcys_ (see p.

401). Although these fossils are of such enormous antiquity, the tracheae

can, M. Brongniart says, be still perceived in these processes.

The Platypterides include also a considerable number of Insects of large

size, with four large equal wings, frequently spotted or variegate. Some of

these Insects were provided with expansions or lobes on the sides of the

prothorax (Fig. 213); these are looked on as analogous to the expansions of

meso- and meta-thorax, which are supposed by some writers to have been the

rudiments from which wings were developed. These prothoracic

wing-rudiments, if such they be, are said to have a system of nervures

similar to what we find in true wings. The genus _Lithomantis_ includes a

Scotch fossil, and has already been mentioned by us on p. 259.

[Illustration: FIG. 213.—_Lithomantis carbonaria_. Carboniferous strata of

Commentry, France. (After Brongniart.)]

The third family of extinct carboniferous Neuroptera is the

Stenodictyopterides, in which Brongniart places the _Dictyoneura_ of

{345}Goldenberg, the North American _Haplophlebium_, and several genera

from Commentry. Some of them were very large Insects, with robust bodies,

and possessed wing-like expansions on the prothorax, and lateral gill-like

appendages on the sides of the abdomen.

It is worthy of note that though so large a number of carboniferous

Neuroptera have now been discovered, no larvae or immature forms have been

found.

We now pass to the consideration of the divisions of Neuroptera still

living.

FAM. I. MALLOPHAGA—BIRD-LICE OR BITING LICE.

_Small Insects, wingless, with large head; thorax usually of two, rarely

of one or three segments; prothorax always distinct; hind body consisting

of eight to ten segments, in addition to the posterior two thoracic

segments which usually are but little or not at all separated from it.

The metamorphosis is very slight. The creatures live on the skins of

birds or mammals, finding nourishment in the epidermal products._

The whole of the Insects of this family live a parasitic, or rather

epizoic, life. They all creep about those parts that are near to the skin,

the feathers of birds or the hair of mammals; they rarely come quite to the

surface, so that they are not detected on a superficial examination. It is

curious that under these circumstances they should exhibit so great a

variety of form and of anatomical characters as they do.

[Illustration: FIG. 214.—_Trinoton luridum_. Lives on the common duck and

various species of _Anas_. (After Giebel.)]

They are very depressed, that is, flat, Insects, with a large head, which

exhibits a great variety of shape; frequently it is provided in front of

the antennae with some peculiar tubercles called trabeculae, which in some

cases are mobile. The antennae are never large, frequently very small; they

consist of from three to five joints, and are sometimes concealed in a

cavity on the under side of the head.

{346}[Illustration: FIG. 215.—Under-surface of head of _Lipeurus

heterographus_. (After Grosse.) _ol_, Labium; _md_, mandible; _mx_,

maxilla; _ul_, labium.]

[Illustration: FIG. 216.—Under lip of _Nirmus_, A; and of _Tetrophthalmus

chilensis_, B. (After Grosse.) _m_, Mentum; _g_, ligula; _pl_, palp; _pg_,

paraglossa; _hy_, lingua.]

The eyes are very rudimentary, and consist of only a small number of

isolated facets placed behind the antennae; sometimes they are completely

absent. The mouth parts are situated entirely on the under-surface of the

head and in a cavity. The upper lip is frequently of remarkable form, as if

it were a scraping instrument (_ol_, Fig. 215). The mandibles are sharply

toothed and apparently act as cutting instruments. The maxillae have been

described in the principal work on the family[270] as possessing in some

cases well-developed palpi. According to Grosse[271] this is erroneous; the

maxillae, he says, are always destitute of palpi, and are of peculiar form,

being each merely a lobe of somewhat conical shape, furnished on one aspect

with hooks or setae. The under lip is peculiar, and apparently of very

different form in the two chief groups of Mallophaga. The large mentum

bears, in Liotheides (Fig. 216, B), on each side a four-jointed palpus, the

pair of palps being very widely separated; the ligula is broad and

undivided; on each side there is a paraglossa bearing an oval process, and

above this is a projection of the hypopharynx. In Philopterides (Fig. 216,

A) the palpi are absent, and the parts of the lower lip are—with the

exception of the paraglossae—but little differentiated. The lingua

(hypo-pharynx) in Mallophaga is largely developed, {347}and bears near the

front a chitinous sclerite corresponding with another placed in the

epipharynx.

The prothorax in Mallophaga is a distinct division of the body even when

the meso- and meta-thorax appear to be part of the abdomen. The mesothorax

is frequently very small; it and the metathorax are sometimes intimately

connected. In other cases (_Laemobothrium_) the metathorax appears to

differ from the following abdominal segment only by having the third pair

of legs attached to it. In _Trinoton_ (Fig. 214) the three thoracic

segments are well developed and distinct. The abdominal segments visible,

vary in number from eight to ten; there is sometimes a difference according

to sex, the male having one segment taken into the interior in connexion

with the reproductive organs. The legs have short, broad coxae and small

tarsi of one or two joints; very rarely three joints are present; there are

either one or two claws; the legs with one claw being adapted for clinging

to or clutching hairs. The front pair of legs is used not for locomotion so

much as for grasping the food and bringing it within the range of the

mouth. No trace of wings has been detected in any species.

[Illustration: FIG. 217.—Ganglia of nervous system of _Lipeurus bacillus_.

(After Giebel.) _a_, Cavity of head.]

The nervous system has been examined by Giebel in _Lipeurus bacillus_;

there is a supra- and an infra-oesophageal ganglion, and three thoracic,

but no abdominal ganglia. The supra-oesophageal is remarkably small, in

fact not larger than the infra-oesophageal; it consists evidently of two

conjoined halves. The alimentary canal has a slender, elongate oesophagus,

dilated behind into a crop; this is frequently received between two cornua

formed by the anterior part of the stomach, which, except for these, is

simply tubular in form, though somewhat narrower at the posterior

extremity. In some forms—Philopterides—the crop is of a very peculiar

nature (Fig. 218), forming an abrupt paunch separated from the stomach by

the {348}posterior portion of the oesophagus. There are only four

Malpighian tubes; in some species the basal half of each tube is much

dilated. The two divisions of the intestine are short and are separated by

the intervention of a glandular girdle. Salivary glands exist; Giebel

figures what we may consider to be an enormous salivary reservoir as

existing in _Menopon leucostomum_.

The testes and ovaries are of a simple nature. The former consist of two or

three capsules, each having a terminal thread; the vasa deferentia are

tortuous and of variable length; they lead into the anterior part of the

ejaculatory duct, where also opens the elongate duct proceeding from the

bicapsular vesicula seminalis; these structures have been figured by

Grosse[272] as well as by Giebel. The ovaries consist of three to five

short egg-tubes on each side; the two oviducts combine to form a short

common duct with which there is connected a receptaculum seminis.

[Illustration: FIG. 218.—Alimentary canal of _Docophorus fuscicollis_.

(After Giebel.) _a_, Oesophagus; _b_, paunch; _a′_, posterior division of

oesophagus; _c_, chylific ventricle or stomach; _d_, Malpighian tubes; _e_,

small intestine; _f_, glandular girdle; _g_, rectum.]

The eggs of some Mallophaga have been figured by Melnikow;[273] they

possess at one extremity a cover with a multiple micropyle-apparatus, and

at the opposite pole are provided with seta-like appendages. They are very

like the eggs of the true lice, and are said in some cases to be suspended

by threads to the hairs or feathers after the fashion of the eggs of

Pediculi.

Little is known as to the development; the young are extremely like the

adult, and are thought to moult frequently; the duration of life is quite

unknown.

It has been stated by some writers that the mouth is truly of the sucking

kind, and that the Mallophaga feed on the blood of their hosts. This is,

however, erroneous; they eat the delicate portions of the feathers of

birds, and of mammals perhaps the young hair. Their fertility is but small,

and it is believed that {349}in a state of nature they are very rarely an

annoyance to their hosts. The majority of the known species live on birds;

the forms that frequent mammals are less varied and have been less studied;

most of them have only one claw to the feet (Fig. 220), while the greater

portion of the avicolous species have two claws.

[Illustration: FIG. 219.—_Lipeurus ternatus_, male; inhabits _Sarcorhamphus

papa_. (After Giebel.)]

[Illustration: FIG. 220.—_Trichodectes latus_, male; inhabits the dog,

_Canis familiaris_.]

Most of the forms have the anterior legs small, and they are usually drawn

towards the mouth, owing, it is believed, to their being used after the

manner of hands to bring the food to the mouth; hence in some of our

figures (219, 220) the body looks as if it had only four legs.

Very diverse statements have been made as to whether allied forms of

Mallophaga are found only on allied birds. It would appear that this is the

case only to a limited extent, as certain species are found on quite a

variety of birds; moreover, some birds harbour several species of

bird-lice, even five genera having been found, it is said, on one species

of bird. _Docophorus icterodes_ has been recorded as occurring on many

kinds of ducks and geese; the swan, however, harbours a distinct species,

_Docophorus cygni_, and this is said to have also been found on the

bean-goose.

At least five species, belonging to three distinct genera, have been found

on the common fowl. The parasite most frequently met with on this valuable

creature is _Menopon pallidum_ (Fig. {350}221), which is said to have been

figured by Redi two hundred years ago under the name of _Pulex capi_. This

species multiplies to a considerable extent; it is of very active habits,

and passes readily from one bird to another, so that it is found on other

species besides the domestic fowl. It is even said that horses kept near

hen-roosts have been seriously troubled by _Menopon pallidum_, but it is

suggested by Osborn that these attacks may perhaps have been really due to

itch-mites. There is, however, no doubt that this species may infest

poultry, especially if sickly, to an enormous extent. The dust-baths in

which poultry are so fond of indulging are considered to be of great use in

keeping down the numbers of this Insect.

[Illustration: FIG. 221.—_Menopon pallidum_; inhabits the common fowl,

_Gallus domesticus_. (After Piaget.)]

A table of the birds and mammals on which Mallophaga have been found,

together with the names of the latter, has been given by Giebel.[274] The

classification of the group, so far as the principal divisions are

concerned, by no means accords with the kind of animals that serve as

hosts, for the only two genera peculiar to quadrupeds (_Trichodectes_, Fig.

220; and _Gyropus_) belong to the two chief divisions of Mallophaga. The

genus _Menopon_ includes numerous species found on birds, and three or four

others peculiar to mammals.

Two very natural divisions, Philopterides and Liotheides, were adopted by

Giebel and Nitzsch, but unfortunately the chief character they made use of

for diagnosing the two groups—the presence or absence of maxillary

palpi—was illusory. Apparently the labial palps will serve the purpose of

distinguishing the two divisions, they being present in the Liotheides and

absent in the Philopterides. A table of the characters of the avicolous

genera of these two groups is given by Grosse.[275]

The Liotheides are more active Insects, and leave their host after its

death to seek another. But the Philopterides do not do so, and die in about

three days after the death of their host. Possibly Mallophaga may be

transferred from one bird to another {351}by means of the parasitic

two-winged flies that infest birds. The writer has recorded[276] a case in

which a specimen of one of these bird-flies captured on the wing was found

to have some Mallophaga attached to it.

We should perhaps point out that these Mallophaga, though called bird-lice,

have nothing to do with the true lice which are so frequently found with

them, and that live by sucking the blood of their hosts. It would in fact

be better to drop the name of bird-lice altogether, and call the Mallophaga

biting lice. _Trichodectes latus_, according to this method, would be known

as the biting louse of the dog, the true or sucking louse of which animal

is _Haematopinus piliferus_, and belongs to the anoplurous division of

Hemiptera.

FAM. II. EMBIIDAE.

_Elongate feeble Insects; with small prothorax, elongate meso- and

meta-thorax, which may either bear wing or be without them. In the former

case these organs are not caducous, are delicately membranous, and all of

one consistence, with three or four indefinite longitudinal nervures and

a few cross-veinlets. The development is incompletely known. The

individuals do not form organised societies._

[Illustration: FIG. 222.—_Oligotoma michaeli._ (After M‘Lachlan.)]

The Embiidae are one of the smallest families of Insects; not more than

twenty species are known from all parts of the world, and it is probable

that only a few hundred actually exist. They are small and feeble Insects

of unattractive appearance, and shrivel so much after death as to render it

difficult to ascertain their characters. They require a warm climate. Hence

{352}it is not a matter for surprise that little should be known about

them.

[Illustration: FIG. 223.—Under-surface of _Embia_ sp. Andalusia.]

The simple antennae are formed of numerous joints, probably varying in

number from about fifteen to twenty-four. The mouth is mandibulate. Chatin

states[277] that the pieces homologous with those of a maxilla can be

detected in the mandible of _Embia_. The labium is divided. The legs are

inserted at the sides of the body, the coxae are widely separated (Fig.

223), the hind pair being, however, more approximate than the others. The

abdomen is simple and cylindrical, consisting of ten segments, the last of

which bears a pair of biarticulate cerci. In the male sex there is a slight

asymmetry of these cerci and of the terminal segment. The thorax is

remarkable on account of the equal development of the meso- and meta-thorax

and their elongation in comparison to the prothorax. When they bear wings

there is no modification or combination of the segments for the purposes of

flight, the condition of these parts being, even then, that of wingless

Insects; so that the Embiidae that have wings may be described as

apterous-like Insects provided with two pairs of inefficient wings. The

wings are inserted on a small space at the front part of each of the

segments to which they are attached. The legs have three-jointed tarsi, and

are destitute of a terminal appendage between the claws.

[Illustration: FIG. 224.—Anterior wing of _Oligotoma saundersii_: A, the

wing; B, outline of the wing, showing nervures. (After Wood-Mason.) 1,

Costal; 2, subcostal; 3, radial; 4, discoidal; 5, anal nervure.]

The wings in Embiidae are very peculiar; they are extremely {353}flimsy,

and the nervures are ill-developed; stripes of a darker brownish colour

alternate with pallid spaces. We figure the anterior wing of _Oligotoma

saundersii_, after Wood-Mason; but should remark that the neuration is

really less definite than is shown in these figures; the lower one

represents Wood-Mason's interpretation of the nervures. He considers[278]

that the brown bands "mark the original courses of veins which have long

since disappeared." A similar view is taken by Redtenbacher,[279] but at

present it rests on no positive evidence.

One of the most curious features of the external structure is the complex

condition of the thoracic sternal sclerites. These are shown in Fig. 223,

representing the under-surface of an _Embia_ of uncertain species recently

brought by Mr. Bateson from Andalusia.

According to Grassi[280] there are ten pairs of stigmata, two thoracic and

eight abdominal; these are connected by longitudinal and transverse

tracheae into a single system. The ganglia of the ventral chain are, one

suboesophageal, three thoracic, and seven abdominal; these are segmentally

placed, except that there is no ganglion in the fifth abdominal segment.

There is a stomato-gastric system but no "sympathetic." Salivary glands are

present. The stomodaeal portions of the alimentary canal are remarkably

capacious; the stomach is elongate and slender, without diverticula; the

Malpighian tubes are elongate and slender; they vary in number with the age

of the individual, attaining that of twenty in the adult. The ovaries are

arranged somewhat after the fashion of those of _Japyx_, there being in

each five short egg-tubes, opening at equal intervals into a straight duct.

The testes are remarkably large; each one consists of five masses of

lobules, and has a large vesicula seminalis, into the posterior part of

which there open the ducts of two accessory glands. The large joint of the

front tarsus includes glands whose secretion escapes by orifices at the

tips of certain setae interspersed between the short spines that are placed

on the sole.

Species of this genus occur in the Mediterranean region, but their

characters have not yet been examined. Our information {354}as to these is

chiefly to be found in Grassi's work. The two species studied by him were

wingless. They live under stones, where they spin webs by means of the

front feet, whose first joint is, as we have said, enlarged and contains

glands; the Insect uses the webs as a means of support in progression,

acting on them by means of papillae and a comb-like structure placed on the

four posterior feet.

Grassi informs us that these Insects are not uncommon under stones in

Catania; they require moisture as well as warmth, but not too much;

sometimes there is only one individual found under a stone, at others eight

or ten. In the winter and spring their galleries are found on the surface

of the earth, but in the hot months of summer they secure the requisite

amount of moisture by sinking their galleries to the depth of ten or

fifteen centimetres. Their food consists chiefly of vegetable matter. They

may be reared with ease in glass vessels. Other species of the family

attain wings; the details of the process are not well known. _Oligotoma

michaeli_ (Fig. 222) was discovered in a hothouse in London among some

orchid roots brought from India, and was found in more than one stage of

development; the young greatly resemble the adult, except in the absence of

wings. A nymph-form is described by M‘Lachlan[281] as possessing wings of

intermediate length, and Hagen has suggested that this supposed nymph is

really an adult female with short wings. If this latter view be correct,

nothing is known as to the mode of development of wings in the family. It

is still uncertain whether female Embiidae ever possess wings. Wood-Mason

and Grassi have shown that there are wingless females in some species, and

we know that there are winged males in others, but what the usual relation

of the sexes may be in this respect is quite uncertain. These Insects have

been detected in various parts of the world. In the Sandwich Islands

_Oligotoma insularis_ was discovered by the Rev. T. Blackburn in the wood

and thatch forming the roofs of natives' houses. A species has been found

in Prussian amber, and Grassi thinks that _Embia solieri_—one of the

Mediterranean species—is not to be distinguished with certainty from the

Insect found in amber.

Embiidae still remains one of the most enigmatic of the families of

Insects. Although Grassi's recent observations are {355}of great value from

an anatomical point of view, they rather add to, than diminish, the

difficulties we encounter in endeavouring to understand the lives of these

obscure creatures. That Embiidae form webs has long been known, and it was

thought by some that the webs, like those of spiders, might be of

assistance in procuring food. We may, however, infer from Grassi's

observations that this is not the case, but that the silken tunnels or

galleries—as he calls them—serve chiefly as a means of locomotion and

protection, the feet of the Insects being highly modified in conformity

with this mode of life. Grassi seems to be of opinion that the galleries

are also useful in preserving a proper degree of humidity round the

Insects. We have already alluded to the mystery that surrounds the mode of

growth of their wings. Nearly all that is known as to the Embiidae is

contained in Grassi's paper, or is referred to in Hagen's monograph of the

family.[282]

Considerable difference of opinion has prevailed as to the allies of these

obscure Insects. It would seem that they are most nearly allied to

Termitidae and Psocidae. Grassi, however, considers these affinities only

remote, and suggests that Embiidae should form a separate Order, to be

placed in a super-Order Orthoptera, which would include our Aptera, the two

families mentioned above, Mallophaga, Embiidae, and the ordinary

Orthoptera. Brauer places the family in his Orthoptera genuina.

{356}CHAPTER XVI

NEUROPTERA _CONTINUED_—TERMITIDAE, TERMITES OR WHITE ANTS

FAM. III. TERMITIDAE—WHITE ANTS, TERMITES.

[Illustration: FIG. 225.—_Termes_ (_Hodotermes_) _mossambicus_. Winged

adult. (After Hagen.)]

_Each species is social, and consists of winged and wingless individuals.

The four wings are, in repose, laid flat on the back, so that the upper

one only is seen except just at the bases; they are membranous and very

elongate, so that they extend far beyond the apex of the abdomen; the

hind pair is remarkably similar in size, form, and consistence to the

front pair: near the base of each wing there is a suture, or line of

weakness, along which the wings can be broken off, the stumps in that

case remaining as short horny flaps reposing on the back. Ligula

channelled but not divided into two parts. The wingless individuals are

very numerous, and have the head and thirteen body segments distinct; the

body {357}is terminated by a pair of short cerci. The metamorphosis is

slight and gradual, and in some individuals is dispensed with._

The term White Ants has been so long in use for the Termitidae that it

appears almost hopeless to replace it in popular use by another word. It

has, however, always given rise to a great deal of confusion by leading

people to suppose that white ants differ chiefly from ordinary ants by

their colour. This is a most erroneous idea. There are scarcely any two

divisions of Insects more different than the white ants and the ordinary

ants. The two groups have little in common except that both have a social

life, and that a very interesting analogy exists between the forms of the

workers and soldiers of these two dissimilar Orders of Insects, giving rise

to numerous analogies of habits. The word Termites—pronounced as two

syllables—is a less objectionable name for these Insects than white ants.

The integument in Termites is delicate, and the chitinous plates are never

very hard; frequently they are so slightly developed that the creature

appears to consist of a single membranous sac with creases in it, the head

alone being very distinct. The head is exserted, frequently of large size,

sometimes as large as all the rest of the body together. Termites may be

quite blind, or possess facetted and simple eyes, the latter when present

being two in number and always accompanied by facetted eyes. The antennae

are simple, consisting of from nine to thirty-one joints, which differ but

little from one another; the number in each individual increases as the

development progresses. The parts of the mouth are large, the ligula

consists of one piece (Fig. 226, A), but often has the appearance of being

formed by two united pieces; on its extremity are seated two pairs of

lobes.

[Illustration: FIG. 226.—_Termes bellicosus._ Labium, A, maxilla, B, of

winged adult; lower face of each. (After Hagen.)]

The head is articulated to the thorax by means of two very large cervical

sclerites on each side, placed at right angles to one another, and visible

on the under-surface. The prothorax is well developed and distinct from the

parts behind it. The {358}pronotum, of variable form and size, is very

distinct in the perfect Insects; with it are connected the largely

developed pleura. The episternum is very peculiar, consisting of an

elongate chitinous slip on each side hanging downwards, the two not quite

meeting in the middle; they thus form the margin of the very large anterior

orifice, and are in contiguity with the cervical sclerites; behind them are

the very large epimera. The prosternum appears to be usually entirely

membranous; in some cases the sclerite in it is small and delicate, and

apparently differs according to the species. The meso- and meta-thorax are

sub-equal in size; the mesosternum forms a peculiar, large, adpressed fold.

The metasternum is membranous, but is terminated behind by a sclerite

apparently of variable form. The hind body is voluminous, simple in form,

consisting of ten segments and bearing at the extremity two short distant

cerci of a variable number of joints. The terminal ventral sclerites differ

greatly in form according to the species and sometimes according to the

sex; there are sometimes, if not always, present near the extremity two

peculiar minute biarticulate styles, called appendices anales. The coxae

are all large, free, and exserted; at the base of each is a transverse

trochantin. The femora are articulated with the trochanters, not with the

coxae; both femora and tibiae are slender, the tarsi small, four-jointed;

the terminal joint elongate.

[Illustration: FIG. 227.—Front tibia and tarsus of _Calotermes rugosus_

larva, showing auditory organ. × 90. (After F. Müller.)]

It is now well established that Termites have a means of communication by

sounds. The individuals have a peculiar way of jerking themselves, as has

been frequently noticed by observers of the Insects; these convulsive

movements may possibly be connected with the production of sound, which may

perhaps be evoked by contact between the back of the head and the pronotum;

the exact mode by which the sounds are produced is not, however, known. The

existence of an auditory organ in the front tibia has been demonstrated by

Fritz Müller,[283] and we reproduce (Fig. 227) one of his figures. The

structure seems to {359}be in plan and position similar to the ear of

Locustidae, though much less perfect.

[Illustration: FIG. 228.—Wings of Termites: A, _Termes lucifugus_; B,

_Hodotermes brunneicornis_; C, _Culotermes nodulosus_. (After Redtenbacher:

B and C diagrammatic.) III, V, VII, homologous areas and nervures according

to Redtenbacher. 1, Costal; 2, subcostal; 3, median; 4, submedian nervures

according to Hagen.]

The wings of Termitidae are not like those of any other Insects; their

neuration is very simple, but nevertheless the wings of the different forms

exhibit great differences in the extent to which they are made up of the

various fields. This is shown in Fig. 228, where the homologous nervures

are numbered according to the systems of both Hagen and Redtenbacher. The

area, VII, that forms the larger part of the wing in C, corresponds to the

small portion at the base of the wing in B. The most remarkable feature of

the wing is, however, its division into two parts by a suture or line of

weakness near the base, as shown in Fig. 225. The wings are used only for a

single flight, and are then shed by detachment at this suture; the small

basal portion of each of the four wings is horny and remains attached to

the Insect, serving as a protection to the dorsal surface of the thorax.

The nature of the suture that enables the Termites to cast their wings with

such ease after swarming is not yet understood. There are no true

transverse veinlets or nervules in Termites. Redtenbacher suggests[284]

that the transverse division of the wing at its base, as shown in Fig. 225,

along which the separation of the wing occurs at its falling off, may have

arisen from a coalescence of the subcostal vein with the eighth concave

vein of such a wing as that of Blattidae. The same authority also informs

us that the only point of resemblance between the wings of Termitidae and

those of Psocidae is that both have an unusually small number of concave

veins.

The information that exists as to the internal anatomy of {360}Termites is

imperfect, and refers, moreover, to different species; it would appear that

considerable diversity exists in many respects, but on this point it would

be premature to generalise. What we know as to the respiratory system is

chiefly due to F. Müller.[285] The number of spiracles is ten; Hagen says

three thoracic and seven abdominal, Müller two thoracic and eight

abdominal. In fertile queens there usually exist only six abdominal

stigmata. There is good reason for supposing that the respiratory system

undergoes much change correlative with the development of the individual;

it has been suggested that the supply of tracheae to the sexual organs is

deficient where there is arrest of development of the latter.

The alimentary canal is only of moderate length. Salivary glands exist, as

also do salivary reservoirs; these latter are large, in some species

remarkably so. The oesophagus is slender, but abruptly enlarged behind to

form a large crop; a proventriculus is apparently either present or absent;

the chylific ventricle, or stomach, is slender and simple. The Malpighian

tubules are very long; their number is probably from four to eight in the

adult, and in the earlier stages less. Behind the tubes the alimentary

canal forms a large paunch, and after this there is a small intestine and

rectum. The paunch is a peculiar structure, and probably of great

importance in the economy of Termites.

These creatures emit minute quantities of a secretion that is corrosive,

and can act on metal and even glass;[286] its nature and source are not

understood. Hagen describes peculiar structures in the rectum to which he

is inclined[287] to ascribe the origin of this substance, but this is very

uncertain.

[Illustration: FIG. 229.—Head and alimentary canal of _Termes lucifugus_

(nymph). _a_, head; _b_, salivary glands; _c_, salivary receptacles; _d_,

crop; _e_, stomach; _f_, intestinal paunch; _g_, small, _h_, large

intestine; _i_, Malpighian tubes; _k_, extremity of body. (After Dufour.)]

The brain is small; the infra-oesophageal ganglion is placed

{361}immediately under the supra-oesophageal; there are three thoracic and

six abdominal ganglia. The nervous system apparently differs but little in

the various forms, or in the different stages of life, except that in the

fertile females the abdominal ganglia become so much enlarged that they

even exceed the brain in size.

The testes are unusually simple; each consists of eight capsules opening

into the vas deferens; the two vasa converge and are continued as a short

ejaculatory duct; at the point of convergence there is a pair of curled

vesiculae seminales.

The ovarian system is also simple; there is a variable number of elongate

egg-tubes, each of which opens separately into the oviduct; the two ducts

unite to form a short uterus, on which there is placed first a spermatheca,

and near the extremity a convolute tubular sebific gland. The number of

egg-tubes is subject to extraordinary variation, according to the species,

and according to the age of the fertilised individual.

SOCIAL LIFE.—Termites live in communities that consist sometimes of

enormous numbers of individuals. The adult forms found in a community are

(1) workers; (2) soldiers; (3) winged males and females; (4) some of these

winged forms that have lost their wings. Some species have no worker caste.

The individuals of the third category are only present for a few days and

then leave the nest in swarms. In addition to the adult individuals there

are also present various forms of young. The individuals that have lost

their wings are usually limited to a single pair, king and queen; there may

be more than one king and queen, but this is not usual. The king and queen

may be recognised by the stumps of their cast wings, which exist in the

form of small triangular pieces folded on the back of the thorax (Fig.

235). The continuance of the community is effected entirely by the royal

pair; they are the centres of activity of the community, which is thrown

into disorder when anything happens to them. Usually the pair are

physically incapable of leaving the nest, especially the queen, and

frequently they are enclosed in a cell which they cannot leave. In

consequence of the disorganisation that arises in the community in the

absence of a royal pair, Termites keep certain individuals in such a state

of advancement that they can rapidly be developed into royalties should

occasion require it. These reserve individuals are called complementary by

Grassi; when {362}they become royalties they are usually immature as

regards the condition of the anterior parts of the body, and are then

called by Grassi and others neoteinic, as is more fully explained on p.

380.

SWARMS.—As a result of the Termite economy large numbers of superfluous

individuals are frequently produced; these, in the winged state, leave the

community, forming swarms which are sometimes of enormous extent, and are

eagerly preyed on by a variety of animals including even man. Hagen has

given particulars[288] of a swarm of _T. flavipes_ in Massachusetts, where

the Insects formed a dark cloud; they were accompanied by no less than

fifteen species of birds, some of which so gorged themselves that they

could not close their beaks.

There is but little metamorphosis in Termitidae. Young Termites are very

soft; they have a thin skin, a disproportionately large head, and are of a

peculiar white colour as if filled with milk. This condition of milkiness

they retain, notwithstanding the changes of form that may occur during

their growth, until they are adult. The wings first appear in the form of

prolongations of the meso- and meta-nota, which increase in size, the

increment probably taking place at the moults. The number of joints of the

antennae increases during the development; it is effected by growth of the

third joint and subsequent division thereof; hence the joints immediately

beyond the second are younger than the others, and are usually shorter and

altogether more imperfect. The life-histories of Termites have been by no

means completely followed; a fact we can well understand when we recollect

that these creatures live in communities concealed from observation, and

that an isolated individual cannot thrive; besides this the growth is, for

Insects, unusually slow.

NATURAL HISTORY.—The progress of knowledge as to Termites has shown that

profound differences exist in the economy of different species, so that no

fair general idea of their lives can be gathered from one species. We will

therefore briefly sketch the economy, so far as it has been ascertained, in

three species, viz. _Calotermes flavicollis_, _Termes lucifugus_, and _T.

bellicosus_.

{363}[Illustration: FIG. 230.—Some individuals of _Calotermes flavicollis_:

A, nymph with partially grown wing-pads; B, adult soldier; C, adult winged

individual. (After Grassi.)]