In another experiment, M. Huber confined a swarm so that they had

access to nothing beside honey, and five times successively removed the

combs with the precaution of preventing the escape of the bees from

the apartment. On each occasion they produced new combs, which puts it

beyond dispute that honey is sufficient to effect the secretion of wax

without the aid of pollen. Instead of supplying the bees with honey,

they were subsequently fed, exclusively, on pollen and fruit; but

though they were kept in captivity for eight days under a bell-glass,

with a comb containing nothing but farina, they neither made wax nor

was any secreted under the rings. In another series of experiments, in

which bees were fed with different sorts of sugar, it was found that

nearly one-sixth of the sugar was converted into wax, dark-coloured

sugar yielding more than double the quantity of refined sugar.

It may not be out of place to subjoin the few anatomical and

physiological facts which have been ascertained by Huber, Maddle,

Jurine, and Latreille.

[Illustration: Worker-bee, magnified--showing the position of the

scales of Wax.]

The first stomach of the worker-bee, according to Latreille,[AG] is

appropriated to the reception of honey, but this is never found in the

second stomach, which is surrounded with muscular rings, and from one

end to the other very much resembles a cask covered with hoops. It is

within these rings that the wax is produced; but the secreting vessels

for this purpose have hitherto escaped the researches of the acutest

naturalists. Huber, however, plausibly enough conjectures that they are

contained in the internal lining of the wax-pockets, which consists

of a cellular substance reticulated with hexagons. The wax-pockets

themselves, which are concealed by the overlapping of the rings, may

be seen by pressing the abdomen of a worker-bee so as to lengthen it,

and separate the rings further from each other. When this has been

done, there may be seen on each of the four intermediate hoops of

the belly, and separated by what may be called the keel (_carina_),

two whitish-coloured pouches, of a soft texture, and in the form of

a trapezium. Within, the little plates or scales of wax are produced

from time to time, and are removed and employed as we shall presently

see. We may remark, that it is chiefly the wax-workers which produce

the wax; for though the nurse-bees are furnished with wax-pockets, they

secrete it only in very small quantities; while in the queen-bee, and

the males or drones, no pockets are discoverable.

[Illustration: Abdomen of Wax-worker Bee.]

"All the scales," says Huber, "are not alike in every bee, for a

difference is perceptible in consistence, shape, and thickness; some

are so thin and transparent as to require a magnifier to be recognised,

or we have been able to discover nothing but spiculæ similar to those

of water freezing. Neither the spiculæ nor the scales rest immediately

on the membrane of the pocket, a slight liquid medium is interposed,

serving to lubricate the joinings of the rings, or to render the

extraction of the scales easier, as otherwise they might adhere too

firmly to the sides of the pockets." M. Huber has seen the scales so

large as to project beyond the rings, being visible without stretching

the segments, and of a whitish yellow, from greater thickness lessening

their transparency. These shades of difference in the scales of various

bees, their enlarged dimensions, the fluid interposed beneath them, the

correspondence between the scale and the size and form of the pockets,

seem to infer the oozing of this substance through the membranes

whereon it is moulded. He was confirmed in this opinion by the escape

of a transparent fluid on piercing the membrane, whose internal surface

seemed to be applied to the soft parts of the belly. This he found

coagulated in cooling, when it resembled wax, and again liquefied on

exposure to heat. The scales themselves, also, melted and coagulated

like wax.[AH]

By chemical analysis, however, it appears that the wax of the rings

is a more simple substance than that which composes the cells; for

the latter is soluble in ether, and in spirit of turpentine, while

the former is insoluble in ether, and but partially soluble in spirit

of turpentine. It should seem to follow, that if the substance found

lying under the rings be really the elements of wax, it undergoes

some subsequent preparation after it is detached; and that the bees,

in short, are capable of impregnating it with matter, imparting to it

whiteness and ductility, whereas in its unprepared state it is only

fusible.

Propolis.

Wax is not the only material employed by bees in their architecture.

Beside this, they make use of a brown, odoriferous, resinous substance,

called _propolis_,[AI] more tenacious and extensible than wax, and

well adapted for cementing and varnishing. It was strongly suspected

by Réaumur that the bees collected the propolis from those trees which

are known to produce a similar gummy resin, such as the poplar, the

birch, and the willow; but he was thrown into doubt by not being able

to detect the bees in the act of procuring it, and by observing them

to collect it where none of those trees, nor any other of the same

description, grew. His bees also refused to make use of bitumen, and

other resinous substances, with which he supplied them, though Mr.

Knight, as we shall afterwards see, was more successful.[AJ]

Long before the time of Réaumur, however, Mouffet, in his _Insectarum

Theatrum_, quotes Cordus for the opinion that propolis is collected

from the buds of trees, such as the poplar and birch; and Reim says

it is collected from the pine and fir.[AK] Huber at length set

the question at rest; and his experiments and observations are so

interesting, that we shall give them in his own words:--

"For many years," says he, "I had fruitlessly endeavoured to find them

on trees producing an analogous substance, though multitudes had been

seen returning laden with it.

"In July, some branches of the wild poplar, which had been cut since

spring, with very large buds, full of a reddish, viscous, odoriferous

matter, were brought to me, and I planted them in vessels before hives,

in the way of the bees going out to forage, so that they could not be

insensible of their presence. Within a quarter of an hour, they were

visited by a bee, which separating the sheath of a bud with its teeth,

drew out threads of the viscous substance, and lodged a pellet of it

in one of the baskets of its limbs; from another bud it collected

another pellet for the opposite limb, and departed to the hive. A

second bee took the place of the former in a few minutes, following

the same procedure. Young shoots of poplar, recently cut, did not seem

to attract these insects, as their viscous matter had less consistence

than the former.[AL]

"Different experiments proved the identity of this substance with the

propolis; and now, having only to discover how the bees applied it to

use, we peopled a hive, so prepared as to fulfil our views. The bees,

building upwards, soon reached the glass above; but, unable to quit

their habitation, on account of rain, they were three weeks without

bringing home propolis. Their combs remained perfectly white until

the beginning of July, when the state of the atmosphere became more

favourable for our observations. Serene, warm weather engaged them to

forage, and they returned from the fields laden with a resinous gum,

resembling a transparent jelly, and having the colour and lustre of

the garnet. It was easily distinguished from the farinaceous pellets

then collected by other bees. The workers bearing the propolis ran over

the clusters, suspended from the roof of the hive, and rested on the

rods supporting the combs, or sometimes stopped on the sides of their

dwelling, in expectation of their companions coming to disencumber them

of their burthen. We actually saw two or three arrive, and carry the

propolis from off the limbs of each with their teeth. The upper part

of the hive exhibited the most animated spectacle; thither a multitude

of bees resorted from all quarters, to engage in the predominant

occupation of the collection, distribution, and application of the

propolis. Some conveyed that of which they had unloaded the purveyors

in their teeth, and deposited it in heaps; others hastened, before its

hardening, to spread it out like a varnish, or formed it into strings,

proportioned to the interstices of the sides of the hives to be filled

up. Nothing could be more diversified than the operations carried on.

"The bees, apparently charged with applying the propolis within the

cells, were easily distinguished from the multitude of workers, by the

direction of their heads towards the horizontal pane forming the roof

of the hive, and on reaching it, they deposited their burthen nearly

in the middle of intervals separating the combs: then they conveyed

the propolis to the real place of its destination. They suspended

themselves by the claws of the hind legs to points of support, afforded

by the viscosity of the propolis on the glass; and, as it were,

swinging themselves backwards and forwards, brought the heap of this

substance nearer to the cells at each impulse. Here the bees employed

their fore feet, which remained free, to sweep what the teeth had

detached, and to unite the fragments scattered over the glass, which

recovered all its transparency when the whole propolis was brought to

the vicinity of the cells.

"After some of the bees had smoothed down and cleaned out the glazed

cells, feeling the way with their antennæ, one desisted, and having

approached a heap of propolis, drew out a thread with its teeth. This

being broken off, it was taken in the claws of the fore feet, and the

bee, re-entering the cell, immediately placed it in the angle of two

portions that had been smoothed, in which operation the fore feet and

teeth were used alternately; but probably proving too clumsy, the

thread was reduced and polished; and we admired the accuracy with which

it was adjusted when the work was completed. The insect did not stop

here: returning to the cell, it prepared other parts of it to receive

a second thread, for which we did not doubt that the heap would be

resorted to. Contrary to our expectation, however, it availed itself

of the portion of the thread cut off on the former occasion, arranged

it in the appointed place, and gave it all the solidity and finish

of which it was susceptible. Other bees completed the work which the

first had begun: and the sides of the cells were speedily secured with

threads of propolis, while some were also put on the orifices; but we

could not seize the moment when they were varnished, though it may be

easily conceived how it is done."[AM]

This is not the only use to which bees apply the propolis. They are

extremely solicitous to remove such insects or foreign bodies as happen

to get admission into the hive. When so light as not to exceed their

powers, they first kill the insect with their stings, and then drag it

out with their teeth. But it sometimes happens, as was first observed

by Maraldi, and since by Réaumur and others, that an ill-fated slug

creeps into the hive: this is no sooner perceived than it is attacked

on all sides, and stung to death. But how are the bees to carry out

so heavy a burthen? Such a labour would be in vain. To prevent the

noxious smell which would arise from its putrefaction, they immediately

embalm it, by covering every part of its body with propolis, through

which no effluvia can escape. When a snail with a shell gets entrance,

to dispose of it gives much less trouble and expense to the bees. As

soon as it receives the first wound from a sting, it naturally retires

within its shell. In this case, the bees, instead of pasting it all

over with propolis, content themselves with gluing all round the

margin of the shell, which is sufficient to render the animal for ever

immovably fixed.

Mr. Knight, the learned and ingenious President of the Horticultural

Society, discovered by accident an artificial substance, more

attractive than any of the resins experimentally tried by Réaumur.

Having caused the decorticated part of a tree to be covered with a

cement composed of bees'-wax and turpentine, he observed that this was

frequented by hive-bees, who, finding it to be a very good propolis

ready made, detached it from the tree with their mandibles, and then,

as usual, passed it from the first leg to the second, and so on. When

one bee had thus collected its load, another often came behind and

despoiled it of all it had collected; a second and a third load were

frequently lost in the same manner; and yet the patient insect pursued

its operations without manifesting any signs of anger.[AN] Probably

the latter circumstance, at which Mr. Knight seems to have been

surprised, was nothing more than an instance of the division of labour

so strikingly exemplified in every part of the economy of bees.

[Illustration: Structure of the legs of the Bee, for carrying propolis

and pollen, magnified.]

It may not be out of place here to describe the apparatus with which

the worker-bees are provided for the purpose of carrying the propolis

as well as the pollen of flowers to the hive, and which has just been

alluded to in the observations of Mr. Knight. The shin or middle

portion of the hind pair of legs is actually formed into a triangular

basket, admirably adapted to this design. The bottom of this basket is

composed of a smooth, shining, horn-like substance, hollowed out in

the substance of the limb, and surrounded with a margin of strong and

thickly-set bristles. Whatever materials, therefore, may be placed by

the bee in the interior of this basket, are secured from falling out by

the bristles around it, whose elasticity will even allow the load to be

heaped beyond their points without letting it fall.

In the case of propolis, when the bee is loading her singular basket,

she first kneads the piece she has detached with her mandibles, till it

becomes somewhat dry and less adhesive, as otherwise it would stick to

her limbs. This preliminary process sometimes occupies nearly half an

hour. She then passes it backwards by means of her feet to the cavity

of her basket, giving it two or three pats to make it adhere; and when

she adds a second portion to the first, she often finds it necessary to

pat it still harder. When she has procured as much as the basket will

conveniently hold, she flies off with it to the hive.

The Building of the Cells.

The notion commonly entertained respecting glass hives is altogether

erroneous. Those who are unacquainted with bees, imagine that, by

means of a glass hive, all their proceedings may be easily watched and

recorded; but it is to be remembered that bees are exceedingly averse

to the intrusion of light, and their first operation in such cases

is to close up every chink by which light can enter to disturb them,

either by clustering together, or by a plaster composed of propolis.

It consequently requires considerable management and ingenuity, even

with the aid of a glass hive, to see them actually at work. M. Huber

employed a hive with leaves, which opened in the manner of a book; and

for some purposes he used a glass box, inserted in the body of the

hive, but easily brought into view by means of screws.

But no invention hitherto contrived is sufficient to obviate every

difficulty. The bees are so eager to afford mutual assistance, and

for this purpose so many of them crowd together in rapid succession,

that the operations of individuals can seldom be traced. Though this

crowding, however, appears to an observer to be not a little confused,

it is all regulated with admirable order, as has been ascertained by

Réaumur and other distinguished naturalists.

When bees begin to build the hive, they divide themselves into bands,

one of which produces materials for the structure; another works

upon these, and forms them into a rough sketch of the dimensions and

partitions of the cells. All this is completed by the second band, who

examine and adjust the angles, remove the superfluous wax, and give

the work its necessary perfection; and a third band brings provisions

to the labourers, who cannot leave their work. But no distribution of

food is made to those whose charge, in collecting propolis and pollen,

calls them to the field, because it is supposed they will hardly forget

themselves; neither is any allowance made to those who begin the

architecture of the cells. Their province is very troublesome, because

they are obliged to level and extend, as well as cut and adjust the

wax to the dimensions required; but then they soon obtain a dismission

from this labour, and retire to the fields to regale themselves with

food, and wear off their fatigue with a more agreeable employment.

Those who succeed them, draw their mouth, their feet, and the extremity

of their body, several times over all the work, and never desist till

the whole is polished and completed; and as they frequently need

refreshments, and yet are not permitted to retire, there are waiters

always attending, who serve them with provisions when they require

them. The labourer who has an appetite, bends down his trunk before the

caterer to intimate that he has an inclination to eat, upon which the

other opens his bag of honey, and pours out a few drops: these may be

distinctly seen rolling through the hole of his trunk, which insensibly

swells in every part the liquor flows through. When this little repast

is over, the labourer returns to his work, and his body and feet repeat

the same motions as before.[AO]

Before they can commence building, however, when a colony or swarm

migrates from the original hive to a new situation, it is necessary

first to collect propolis, with which every chink and cranny in the

place where they mean to build may be carefully stopped up; and

secondly, that a quantity of wax be secreted by the wax-workers to

form the requisite cells. The secretion of wax, it would appear, goes

on best when the bees are in a state of repose; and the wax-workers,

accordingly, suspend themselves in the interior in an extended cluster,

like the curtain which is composed of a series of intertwined festoons

or garlands, crossing each other in all directions--the uppermost bee

maintaining its position by laying hold of the roof with its fore legs,

and the succeeding one by laying hold of the hind legs of the first.

[Illustration: Curtain of Wax-workers secreting wax.]

"A person," says Réaumur, "must have been born devoid of curiosity not

to take interest in the investigation of such wonderful proceedings."

Yet Réaumur himself seems not to have understood that the bees

suspended themselves in this manner to secrete wax, but merely, as he

imagined, to recruit themselves by rest for renewing their labours.

The bees composing the festooned curtain are individually motionless;

but this curtain is, notwithstanding, kept moving by the proceedings

in the interior; for the nurse-bees never form any portion of it,

and continue their activity--a distinction with which Réaumur was

unacquainted.

Although there are many thousand labourers in a hive, they do not

commence foundations for combs in several places at once, but wait

till an individual bee has selected a site, and laid the foundation of

a comb, which serves as a directing mark for all that are to follow.

Were we not expressly told by so accurate an observer as Huber, we

might hesitate to believe that bees, though united in what appears

to be an harmonious monarchy, are strangers to subordination, and

subject to no discipline. Hence it is, that though many bees work on

the same comb, they do not appear to be guided by any simultaneous

impulse. The stimulus which moves them is successive. An individual

bee commences each operation, and several others successively apply

themselves to accomplish the same purpose. Each bee appears, therefore,

to act individually, either as directed by the bees preceding it,

or by the state of advancement in which it finds the work it has to

proceed with. If there be anything like unanimous consent, it is the

inaction of several thousand workers while a single individual proceeds

to determine and lay down the foundation of the first comb. Réaumur

regrets that, though he could by snatches detect a bee at work in

founding cells or perfecting their structure, his observations were

generally interrupted by the crowding of other bees between him and

the little builder. He was therefore compelled rather to infer the

different steps of their procedure from an examination of the cells

when completed, than from actual observation. The ingenuity of Huber,

even under all the disadvantages of blindness, succeeded in tracing the

minutest operations of the workers from the first waxen plate of the

foundation. We think the narrative of the discoverer's experiments,

as given by himself, will be more interesting than any abstract of it

which we could furnish:--

"Having taken a large bell-shaped glass receiver, we glued thin wooden

slips to the arch at certain intervals, because the glass itself was

too smooth to admit of the bees supporting themselves on it. A swarm,

consisting of some thousand workers, several hundred males, and a

fertile queen, was introduced, and they soon ascended to the top.

Those first gaining the slips fixed themselves there by the fore-feet;

others, scrambling up the sides, joined them, by holding their legs

with their own, and they thus formed a kind of chain, fastened by the

two ends to the upper parts of the receiver, and served as ladders or a

bridge to the workers enlarging their number. The latter were united in

a cluster, hanging like an inverted pyramid from the top to the bottom

of the hive.

"The country then affording little honey, we provided the bees with

syrup of sugar, in order to hasten their labour. They crowded to the

edge of a vessel containing it; and, having satisfied themselves,

returned to the group. We were now struck with the absolute repose of

this hive, contrasted with the usual agitation of bees. Meanwhile,

the nurse-bees alone went to forage in the country; they returned

with pollen, kept guard at the entrance of the hive, cleansed it, and

stopped up its edges with propolis. The wax-workers remained motionless

about fifteen hours: the curtain of bees, consisting always of the same

individuals, assured us that none replaced them. Some hours later, we

remarked that almost all these individuals had wax scales under the

rings; and next day this phenomenon was still more general. The bees

forming the external layer of the cluster, having now somewhat altered

their position, enabled us to see their bellies distinctly. By the

projection of the wax scales, the rings seemed edged with white. The

curtain of bees became rent in several places, and some commotion began

to be observed in the hive.

"Convinced that the combs would originate in the centre of the swarm,

our whole attention was then directed towards the roof of the glass. A

worker at this time detached itself from one of the central festoons

of the cluster, separated itself from the crowd, and, with its head,

drove away the bees at the beginning of the row in the middle of the

arch, turning round to form a space an inch or more in diameter, in

which it might move freely. It then fixed itself in the centre of the

space thus cleared.

[Illustration: Wax-worker laying the foundation of the first Cell.]

"The worker now employing the pincers at the joint of one of the third

pair of its limbs, seized a scale of wax projecting from a ring, and

brought it forward to its mouth with the claws of its fore-legs, where

it appeared in a vertical position. We remarked that, with its claws,

it turned the wax in every necessary direction; that the edge of the

scale was immediately broken down, and the fragments having been

accumulated in the hollow of the mandibles, issued forth like a very

narrow ribbon, impregnated with a frothy liquid by the tongue. The

tongue itself assumed the most varied shapes, and executed the most

complicated operations,--being sometimes flattened like a trowel, and

at other times pointed like a pencil; and, after imbuing the whole

substance of the ribbon, pushed it forward again into the mandibles,

whence it was drawn out a second time, but in an opposite direction.

[Illustration: Curtain of Wax-workers (see p. 132).]

"At length the bee applied these particles of wax to the vault of the

hive, where the saliva impregnating them promoted their adhesion, and

also communicated a whiteness and opacity which were wanting when the

scales were detached from the rings. Doubtless this process was to give

the wax that ductility and tenacity belonging to its perfect state.

The bee then separated those portions not yet applied to use with

its mandibles, and with the same organs afterwards arranged them at

pleasure. The founder bee, a name appropriated to this worker, repeated

the same operation, until all the fragments, worked up and impregnated

with the fluid, were attached to the vault, when it repeated the

preceding operations on the part of the scale yet kept apart, and

again united to the rest what was obtained from it. A second and third

scale were similarly treated by the same bee; yet the work was only

sketched; for the worker did nothing but accumulate the particles of

wax together. Meanwhile the founder, quitting its position, disappeared

amidst its companions. Another, with wax under the rings, succeeded

it, which suspending itself to the same spot, withdrew a scale by

the pincers of the hind legs, and passing it through its mandibles,

prosecuted the work; and taking care to make its deposit in a line with

the former, it united their extremities. A third worker, detaching

itself from the interior of the cluster, now came and reduced some of

the scales to paste, and put them near the materials accumulated by

its companions, but not in a straight line. Another bee, apparently

sensible of the defect, removed the misplaced wax before our eyes, and

carrying it to the former heap, deposited it there, exactly in the

order and direction pointed out.

"From all these operations was produced a block of a rugged surface,

hanging down from the arch, without any perceptible angle, or any

traces of cells. It was a simple wall, or ridge, running in a straight

line, and without the least inflection, two-thirds of an inch in

length, above two-thirds of a cell, or two lines, high, and declining

towards the extremities. We have seen other foundation walls from an

inch to an inch and a half long, the form being always the same; but

none ever of greater height.

"The vacuity in the centre of the cluster had permitted us to discover

the first manoeuvres of the bees, and the art with which they laid the

foundations of their edifices. However, it was filled up too soon for

our satisfaction; for workers collecting on both faces of the wall

obstructed our view of their further operations."[AP]

_CHAPTER VI._

ARCHITECTURE OF THE HIVE-BEE CONTINUED--FORM OF THE CELLS.

The obstruction of which M. Huber complains only operated as a

stimulus to his ingenuity in contriving how he might continue his

interesting observations. From the time of Pappus to the present

day, mathematicians have applied the principles of geometry to

explain the construction of the cells of a bee-hive; but though their

extraordinary regularity, and wonderfully-selected form, had so often

been investigated by men of the greatest talent, and skilled in all

the refinements of science, the process by which they are constructed,

involving also the causes of their regularity of form, had not been

traced till M. Huber devoted himself to the inquiry.

As the wax-workers secrete only a limited quantity of wax, it is

indispensably requisite that as little as possible of it should be

consumed, and that none of it should be wasted. Bees, therefore, as

M. Réaumur well remarks,[AQ] have to solve this difficult geometrical

problem:--a quantity of wax being given, to form of it similar and

equal cells of a determinate capacity, but of the largest size in

proportion to the quantity of matter employed, and disposed in such

a manner as to occupy the least possible space in the hive. This

problem is solved by bees in all its conditions. The cylindrical form

would seem to be best adapted to the shape of the insect; but had

the cells been cylindrical, they could not have been applied to each

other without leaving a vacant and superfluous space between every

three contiguous cells. Had the cells, on the other hand, been square

or triangular, they might have been constructed without unnecessary

vacancies; but these forms would have both required more material, and

have been very unsuitable to the shape of a bee's body. The six-sided

form of the cells obviates every objection; and while it fulfils the

conditions of the problem, it is equally adapted with a cylinder to the

shape of the bee.

M. Réaumur further remarks, that the base of each cell, instead of

forming a plane, is usually composed of three pieces in the shape of

the diamonds on playing cards, and placed in such a manner as to form a

hollow pyramid. This structure, it may be observed, imparts a greater

degree of strength, and, still keeping the solution of the problem

in view, gives a great capacity with the smallest expenditure of

material. This has actually, indeed, been ascertained by mathematical

measurement and calculation. Maraldi, the inventor of glass hives,

determined, by minutely measuring these angles, that the greater were

109° 28', and the smaller 70° 32'; and M. Réaumur, being desirous to

know why these particular angles are selected, requested M. Koenig, a

skilful mathematician (without informing him of his design, or telling

him of Maraldi's researches), to determine by calculation what ought

to be the angle of a six-sided cell, with a concave pyramidal base,

formed of three similar and equal rhomboid plates, so that the least

possible matter should enter into its construction. By employing what

geometricians denominate the _infinitesimal calculus_, M. Koenig found

that the angles should be 109° 26' for the greater, and 70° 34' for

the smaller, or about two-sixtieths of a degree, more or less, than

the actual angles made choice of by bees. The equality of inclination

in the angles has also been said to facilitate the construction of the

cells.

M. Huber adds to these remarks, that the cells of the first row, by

which the whole comb is attached to the roof of a hive, are not like

the rest; for, instead of six sides, they have only five, of which

the roof forms one. The base, also, is in these different, consisting

of three pieces on the face of the comb, and on the other side of

two: one of these only is diamond-shaped, while the other two are of

an irregular four-sided figure. This arrangement, by bringing the

greatest number of points in contact with the interior surface, insures

the stability of the comb.

[Illustration: Arrangement of Cells.]

It may, however, be said not to be quite certain, that Réaumur and

others have not ascribed to bees the merit of ingenious mathematical

contrivance and selection, when the construction of the cells may

more probably originate in the form of their mandibles and the other

instruments employed in their operations. In the case of other insects,

we have, both in the preceding and subsequent pages of this volume,

repeatedly noticed, that they use their bodies, or parts thereof, as

the standards of measurement and modelling; and it is not impossible

that bees may proceed on a similar principle. M. Huber replies to this

objection, that bees are not provided with instruments corresponding

to the angles of their cells; for there is no more resemblance between

these and the form of their mandibles, than between the chisel of the

sculptor and the work which he produces. The head, he thinks, does not

furnish any better explanation. He admits that the antennæ are very

flexible, so as to enable the insects to follow the outline of every

object; but concludes that neither their structure, nor that of the

limbs and mandibles, are adequate to explain the form of the cells,

though all these are employed in the operations of building,--the

effect, according to him, depending entirely on the object which the

insect proposes.

We shall now follow M. Huber in the experiments which he contrived, in

order to observe the operations of the bees subsequent to their laying

a foundation for the first cell; and we shall again quote from his own

narrative:--

"It appeared to me," he says, "that the only method of isolating

the architects, and bringing them individually into view, would be

to induce them to change the direction of their operations and work

upwards.

"I had a box made twelve inches square and nine deep, with a moveable

glass lid. Combs, full of brood, honey, and pollen, were next selected

from one of my leaf-hives, as containing what might interest the bees,

and being cut into pieces a foot long, and four inches deep, they were

arranged vertically at the bottom of the box, at the same intervals

as the insects themselves usually leave between them. A small slip

of wooden lath covered the upper edge of each. It was not probable

that the bees would attempt to found new combs on the glass roof of

the box, because its smoothness precluded the swarm from adhering

to it; therefore, if disposed to build, they could do so over the

slips resting on the combs, which left a vacuity five inches high

above them. As we had foreseen, the swarm with which this box was

peopled established itself among the combs below. We then observed the

nurse-bees displaying their natural activity. They dispersed themselves

throughout the hive, to feed the young grubs, to clear out their

lodgment, and adapt it for their convenience. Certainly, the combs,

which were roughly cut to fit the bottom of the box, and in some parts

damaged, appeared to them shapeless and misplaced; for they speedily

commenced their reparation. They beat down the old wax, kneaded it

between their teeth, and thus formed binding materials to consolidate

them. We were astonished beyond expression by such a multitude of

workers employed at once in labours to which it did not appear they

should have been called, at their coincidence, their zeal, and their

prudence.

"But it was still more wonderful, that about half the numerous

population took no part in the proceedings, remaining motionless, while

the others fulfilled the functions required. The wax-workers, in a

state of absolute repose, recalled our former observations. Gorged

with the honey we had put within their reach, and continuing in this

condition during twenty-four hours, wax was formed under their rings,

and was now ready to be put in operation. To our great satisfaction,

we soon saw a little foundation-wall rising on one of the slips that

we had prepared to receive the superstructure. No obstacle was offered

to the progress of our observations; and for the second time we beheld

both the undertaking of the founder-bee, and the successive labours

of several wax-workers, in forming the foundation-wall. Would that my

readers could share the interest which the view of these architects

inspired!

"This foundation, originally very small, was enlarged as the work

required; while they excavated on one side a hollow, of about the width

of a common cell, and on the opposite surface two others somewhat

more elongated. The middle of the single cell corresponded exactly to

the partition separating the latter: the arches of these excavations,

projecting by the accumulation of wax, were converted into ridges in a

straight line; whence the cells of the first row were composed of five

sides, considering the slip as one side, and those of the second row,

of six sides.

[Illustration: Foundation-wall enlarged, and the Cells commenced.]

"The interior conformation of the cavities, apparently, was derived

from the position of their respective outlines. It seemed that the

bees, endowed with an admirable delicacy of feeling, directed their

teeth principally to the place where the wax was thickest; that is, the

parts where other workers on the opposite side had accumulated it; and

this explains why the bottom of the cell is excavated in an angular

direction behind the projection on the sides of which the sides of the

corresponding cells are to rise. The largest of the excavations, which

was opposite to three others, was divided into three parts, while the

excavations of the first row on the other face, applied against this

one, were composed of only two.

"In consequence of the manner in which the excavations were opposed

to each other, those of the second row, and all subsequent, partially

applied to three cavities, were composed of three equal diamond-shaped

lozenges. I may here remark, that each part of the labour of bees

appears the natural result of what has preceded it: therefore, chance

has no share in these admirable combinations.

"A foundation-wall rose above the slip like a minute vertical

partition, five or six lines long, two lines high, but only half a

line in thickness; the edge circular, and the surface rough. Quitting

the cluster among the combs, a nurse-bee mounted the slip, turned

around the block, and visiting both sides, began to work actively

in the middle. It removed as much wax with its teeth as might equal

the diameter of a common cell; and after kneading and moistening the

particles, deposited them on the edge of the excavation. This insect

having laboured some seconds, retired, and was soon replaced by

another; a third continued the work, raising the margin of the edges,

now projecting from the cavity, and with assistance of its teeth and

feet fixing the particles, so as to give these edges a straighter form.

More than twenty bees successively participated in the same work; and

when the cavity was little above a line and a half in height, though

equalling a cell in width, a bee left the swarm, and after encircling

the block, commenced its operations on the opposite face, where

yet untouched. But its teeth acting only on one half of this side,

the hollow which it formed was opposite to only one of the slight

prominences bordering the first cavity. Nearly at the same time another

worker began on the right of the face that had been untouched, wherein

both were occupied in forming cavities which may be designed the second

and third; and they also were replaced by substitutes. These two latter

cavities were separated only by the common margin, framed of particles

of wax withdrawn from them; which margin corresponded with the centre

of the cavity on the opposite surface. The foundation-wall itself was

still of insufficient dimensions to admit the full diameter of a cell:

but while the excavations were deepened, wax-workers, extracting their

scales of wax, applied them in enlarging its circumference; so that it

rose nearly two lines further around the circular arch. The nurse-bees,

which appeared more especially charged with sculpturing the cells,

being then enabled to continue their outlines, prolonged the cavities,

and heightened their margins on the new addition of wax.

"The arch, formed by the edge of each of these cavities, was next

divided as by two equal chords, in the line of which the bees formed

stages or projecting borders, or margins meeting at an obtuse angle:

the cavities now had four margins, two lateral and perpendicular to the

supporting slip, and two oblique, which were shorter.

"Meantime, it became more difficult to follow the operations of the

bees, from their frequently interposing their heads between the eye of

the observer and the bottom of the cell; but the partition, whereon

their teeth laboured, had become so transparent as to expose what

passed on the other side.

"The cavities of which we speak formed the bottom of the first three

cells; and while the bees engaged were advancing them to perfection,

other workers commenced sketching a second row of cells above the

first, and partly behind those in front--for, in general, their labour

proceeds by combination. We cannot say, 'When bees have finished

this cell, they will begin new ones;' but, 'while particular workers

advance a certain portion, we are certain that others will carry on

the adjacent cells.' Further, the work begun on one face of the comb

is already the commencement of that which is to follow on the reverse.

All this depends on a reciprocal relation, or a mutual connexion of the

parts, rendering the whole subservient to each other. It is undoubted,

therefore, that slight irregularities on the front will affect the form

of the cells on the back of the comb."[AR]

When they have in this manner worked the bottoms of the first row of

cells into the required forms, some of the nurse-bees finish them

by imparting a sort of polish, while others proceed to cut out the

rudiments of a second row from a fresh wall of wax which has been built

in the meanwhile by the wax-workers, and also on the opposite side of

this wall; for a comb of cells is always double, being arranged in two

layers, placed end to end. The cells of this second row are engrafted

on the borders of cavities hollowed out in the wall, being founded

by the nurse-bees, bringing the contour of all the bottoms, which is

at first unequal, to the same level; and this level is kept uniform

in the margins of the cells till they are completed. At first sight

nothing appears more simple than adding wax to the margins; but from

the inequalities occasioned by the shape of the bottom, the bees must

accumulate wax on the depressions, in order to bring them to a level.

It follows accordingly that the surface of a new comb is not quite

flat, there being a progressive slope produced as the work proceeds,

and the comb being therefore in the form of a lens, the thickness

decreasing towards the edge, and the last-formed cells being shallower

or shorter than those preceding them. So long as there is room for the

enlargement of the comb, this thinning of its edge may be remarked;

but as soon as the space within the hive prevents its enlargement, the

cells are made equal, and two flat and level surfaces are produced.

M. Huber observed, that while sketching the bottom of a cell, before

there was any upright margin on the reverse, their pressure on the

still soft and flexible wax gave rise to a projection, which sometimes

caused a breach of the partition. This, however, was soon repaired,

but a slight prominence always remained on the opposite surface, to

the right and left of which they placed themselves to begin a new

excavation; and they heaped up part of the materials between the two

flutings formed by their labour. The ridge thus formed becomes a guide

to the direction which the bees are to follow for their vertical furrow

of the front cell.

We have already seen that the first cell determines the place of all

that succeed it, and two of these are never, in ordinary circumstances,

begun in different parts of the hive at the same time, as is alleged

by some early writers. When some rows of cells, however, have been

completed in the first comb, two other foundation-walls are begun, one

on each side of it, at the exact distance of one-third of an inch,

which is sufficient to allow two bees employed on the opposite cells to

pass each other without jostling. These new walls are also parallel to

the former; and two more are afterwards begun exterior to the second,

and at the same parallel distance. The combs are uniformly enlarged,

and lengthened in a progression proportioned to the priority of their

origin; the middle comb being always advanced beyond the two adjoining

ones by several rows of cells, and these again beyond the ones exterior

to them. Did the bees lay the foundations of all their combs at the

same time, they would not find it easy to preserve parallelism and an

equality in their distances. It may be remarked further, that beside

the vacancies of half an inch between the cells, which form what we

call the highways of the community, the combs are pierced in several

places with holes which serve as postern-gates for easy communication

from one to another, to prevent loss of time in going round. The equal

distance between the combs is of more importance to the welfare of the

hive than might at first appear; for were they too distant, the bees

would be so scattered and dispersed, that they could not reciprocally

communicate the heat indispensable for hatching the eggs and rearing

the young. If the combs, on the other hand, were closer, the bees could

not traverse the intervals with the freedom necessary to facilitate the

work of the hive. On the approach of winter, they sometimes elongate

the cells which contain honey, and thus contract the intervals between

the combs. But this expedient is in preparation for a season when it

is important to have copious magazines, and when, their activity being

relaxed, it is unnecessary for their communications to be so spacious

and free. On the return of spring, the bees hasten to contract the

elongated cells, that they may become fit for receiving the eggs which

the queen is about to deposit, and in this manner they re-establish the

regular distance.[AS]

We are indebted to the late Dr. Barclay of Edinburgh, well known as an

excellent anatomist, for the discovery that each cell in a honeycomb is

not simply composed of one wall, but consists of two. We shall give the

account of his discovery in his own words:--

"Having inquired of several naturalists whether or not they knew any

author who had mentioned that the partitions between the cells of the

honeycomb were double, and whether or not they had ever remarked such

a structure themselves, and they having answered in the negative, I

now take the liberty of presenting to the Society pieces of honeycomb,

in which the young bees had been reared, upon breaking which, it will

be clearly seen that the partitions between different cells, at the

sides and the base, are all _double_; or, in other words, that each

cell is a distinct, separate, and in some measure an independent

structure, agglutinated only to the neighbouring cells; and that when

the agglutinating substance is destroyed, each cell may be entirely

separated from the rest.

"I have also some specimens of the cells formed by wasps, which

show that the partitions between them are also double, and that the

agglutinating substance between them is more easily destroyed than that

between the cells of the bee."[AT]

Irregularities in their Workmanship.

Though bees, however, work with great uniformity when circumstances

favour their operations, they may be compelled to vary their

proceedings. M. Huber made several ingenious experiments of this kind.

The following, mentioned by Dr. Bevan, was accidental, and occurred to

his friend Mr. Walond. "Inspecting his bee-boxes at the end of October,

1817, he perceived that a centre comb, burthened with honey, had

separated from its attachments, and was leaning against another comb

so as to prevent the passage of the bees between them. This accident

excited great activity in the colony; but its nature could not be

ascertained at the time. At the end of a week, the weather being cold,

and the bees clustered together Mr. Walond observed, through the window

of the box, that they had constructed two horizontal pillars betwixt

the combs alluded to, and had removed so much of the honey and wax from

the top of each as to allow the passage of a bee: in about ten days

more there was an uninterrupted thoroughfare; the detached comb at its

upper part had been secured by a strong barrier, and fastened to the

window with the spare wax. This being accomplished, the bees removed

the horizontal pillars first constructed, as being of no further

use."[AU]

A similar anecdote is told by M. Huber. "During the winter," says he,

"a comb in one of my bell-glass hives, having been originally insecure,

fell down, but preserved its position parallel to the rest. The bees

were unable to fill up the vacuity left above it, because they do

not build combs of old wax, and none new could be then obtained. At

a more favourable season they would have engrafted a new comb on the

old one; but now their provision of honey could not be spared for

the elaboration of this substance, which induced them to insure the

stability of the comb by another process.

"Crowds of bees taking wax from the lower part of other combs, and even

gnawing it from the surface of the orifices of the deepest cells, they

constructed so many irregular pillars, joists, or buttresses, between

the sides of the fallen comb, and others on the glass of the hive. All

these were artificially adapted to localities. Neither did they confine

themselves to repairing the accidents which their works had sustained.

They seemed to profit by the warning to guard against a similar

casualty.

"The remaining combs were not displaced; therefore, while solidly

adhering by the base, we were greatly surprised to see the bees

strengthen their principal fixtures with old wax. They rendered them

much thicker than before, and fabricated a number of new connections,

to unite them more firmly to each other and to the sides of their

dwelling. All this passed in the middle of January, a time that these

insects commonly keep in the upper part of their hive, and when work is

no longer seasonable."[AV]

M. Huber the younger shrewdly remarks, that the tendency to symmetry

observable in the architecture of bees does not hold so much in small

details as in the whole work, because they are sometimes obliged to

adapt themselves to particular localities. One irregularity leads on

to another, and it commonly arises from mere accident, or from design

on the part of the proprietor of the bees. By allowing, for instance,

too little interval between the spars for receiving the foundation of

the combs, the structure has been continued in a particular direction.

The bees did not at first appear to be sensible of the defect, though

they afterwards began to suspect their error, and were then observed to

change their line of work till they gained the customary distance. The

cells having been by this change of direction in some degree curved,

the new ones which were commenced on each side of it, by being built

everywhere parallel to it, partook of the same curvature. But the bees

did not relish such approaches to the "line of beauty," and exerted

themselves to bring their buildings again into the regular form.

In consequence of several irregularities which they wished to correct,

the younger Huber has seen bees depart from their usual practice, and

at once lay on a spar two foundation-walls not in the same line. They

could consequently neither be enlarged without obstructing both, nor

from their position could the edges unite, had they been prolonged.

The little architects, however, had recourse to a very ingenious

contrivance: they curved the edges of the two combs, and brought them

to unite so neatly that they could be both prolonged in the same line

with ease; and when carried to some little distance, their surface

became quite uniform and level.

"Having seen bees," says the elder Huber, "work both up and down, I

wished to try to investigate whether we could compel them to construct

their combs in any other direction. We endeavoured to puzzle them with

a hive glazed above and below, so that they had no place of support

but the upright sides of their dwelling; but, betaking themselves

to the upper angle, they built combs perpendicular to one of these

sides, and as regularly as those which they usually build under a

horizontal surface. The foundations were laid on a place which does

not serve naturally for the base, yet, except in the difference

of direction, the first row of cells resembled those in ordinary

hives, the others being distributed on both faces, while the bottoms

alternately corresponded with the same symmetry. I put the bees to a

still greater trial. As they now testified their inclination to carry

their combs, by the shortest way, to the opposite side of the hive (for

they prefer uniting them to wood, or a surface rougher than glass), I

covered it with a pane. Whenever this smooth and slippery substance was

interposed between them and the wood, they departed from the straight

line hitherto followed, and bent the structure of their comb at a

right angle to what was already made, so that the prolongation of the

extremity might reach another side of the hive, which had been left

free.

"Varying this experiment in several ways, I saw the bees constantly

change the direction of their combs, when I presented to them a surface

too smooth to admit of their clustering on it. They always sought the

wooden sides. I thus compelled them to curve the combs in the strangest

shapes, by placing a pane at a certain distance from their edges. These

results indicate a degree of instinct truly wonderful. They denote even

more than instinct: for glass is not a substance against which bees can

be warned by nature. In trees, their natural abode, there is nothing

that resembles it, or with the same polish. The most singular part of

their proceeding is changing the direction of the work before arriving

at the surface of the glass, and while yet at a distance suitable for

doing so. Do they anticipate the inconvenience which would attend any

other mode of building? No less curious is the plan adopted by the

bee for producing an angle in the combs: the wonted fashion of their

work, and the dimensions of the cells, must be altered. Therefore, the

cells on the upper or convex side of the combs are enlarged; they are

constructed of three or four times the width of those on the opposite

surface. How can so many insects, occupied at once on the edges of the

combs, concur in giving them a common curvature from one extremity to

the other? How do they resolve on establishing cells so small on one

side, while dimensions so enlarged are bestowed on those of the other?

And is it not still more singular, that they have the art of making a

correspondence between cells of such reciprocal discrepance? The bottom

being common to both, the tubes alone assume a taper form. Perhaps no

other insect has afforded a more decisive proof of the resources of

instinct, when compelled to deviate from the ordinary course.

"But let us study them in their natural state, and there we shall find

that the diameter of their cells must be adapted to the individuals

which shall be bred in them. The cells of males have the same figure,

the same number of lozenges and sides, as those of workers, and angles

of the same size. Their diameter is 3-1/3 lines, while those of workers

are only 2-2/5.

"It is rarely that the cells of males occupy the higher part of the

combs. They are generally in the middle or on the sides, where they

are not isolated. The manner in which they are surrounded by other

cells alone can explain how the transition in size is effected. When

the cells of males are to be fabricated under those of workers, the

bees make several rows of intermediate cells, whose diameter augments

progressively, until gaining that proportion proper to the cells

required; and in returning to those of workers, a lowering is observed

in a manner corresponding.

"Bees, in preparing the cells of males, previously establish a block or

lump of wax on the edge of their comb, thicker than is usually employed

for those of workers. It is also made higher, otherwise the same order

and symmetry could not be preserved on a larger scale.

"Several naturalists notice the irregularities in the cells of bees

as so many defects. What would have been their astonishment had

they observed that part of them are the result of calculation? Had

they followed the imperfection of their organs, some other means

of compensating them would have been granted to the insects. It is

much more surprising that they know how to quit the ordinary route,

when circumstances demand the construction of enlarged cells; and,

after building thirty or forty rows of them, to return to the proper

proportions from which they have departed by successive reductions.

Bees also augment the dimensions of their cells when there is an

opportunity for a great collection of honey. Not only are they then

constructed of a diameter much exceeding that of the common cells, but

they are elongated throughout the whole space admitting it. A great

portion of irregular comb contains cells an inch, or even an inch and a

half, in depth.

"Bees, on the contrary, sometimes are induced to shorten their cells.

When wishing to prolong an old comb, whose cells have received their

full dimensions, they gradually reduce the thickness of its edges,

by gnawing down the sides of the cells, until they restore it to its

original lenticular form. They add a waxen block around the whole

circumference, and on the edge of the comb construct pyramidal bottoms,

such as those fabricated on ordinary occasions. It is a certain fact,

that a comb never is extended in any direction unless the bees have

thinned the edges, which are diminished throughout a sufficient space

to remove any angular projection.

"The law which obliges these insects partly to demolish the cells on

the edges of the comb before enlarging it, unquestionably demands more

profound investigation. How can we account for instinct leading them to

undo what they have executed with the utmost care? The wonted regular

gradation which may be necessary for new cells, subsists among those

adjoining the edges of a comb recently constructed. But afterwards,

when those on the edge are deepened like the cells of the rest of the

surface, the bees no longer preserve the decreasing gradation which is

seen in the new combs."[AW]

The Finishing of the Cells.

While the cells are building they appear to be of a dull white colour,

soft, even, though not smooth, and translucent; but in a few days they

become tinged with yellow, particularly on the interior surface; and

their edges, from being thin, uniform, and yielding, become thicker,

less regular, more heavy, and so firm that they will bend rather

than break. New combs break on the slightest touch. There is also a

glutinous substance observable around the orifices of the yellow cells,

of reddish colour, unctuous, and odoriferous. Threads of the same

substance are applied all around the interior of the cells, and at the

summit of their angles, as if it were for the purpose of binding and

strengthening the walls. These yellow cells also require a much higher

temperature of water to melt them than the white ones.

It appeared evident, therefore, that another substance, different from

wax, had been employed in varnishing the orifices, and strengthening

the interior of the cells. M. Huber, by numerous experiments,

ascertained the resinous threads lining the cells, as well as the

resinous substance around their orifice, to be propolis; for he traced

them, as we mentioned in our account of propolis, from the poplar

buds where they collected it, and saw them apply it to the cells; but

the yellow colour is not imparted by propolis, to which it bears no

analogy. We are, indeed, by no means certain what it is, though it

was proved by experiment not to arise from the heat of the hives, nor

from emanations of honey, nor from particles of pollen. Perhaps it may

be ascribed to the bees rubbing their teeth, feet, and other parts of

their body, on the surfaces where they seem to rest; or to their tongue

(haustellum) sweeping from right to left like a fine pliant pencil,

when it appears to leave some sprinkling of a transparent liquid.

Besides painting and varnishing their cells in this manner, they take

care to strengthen the weaker part of their edifice by means of a

mortar composed of propolis and wax, and named _pissoceros_[AX] by the

ancients who first observed it, though Réaumur was somewhat doubtful

respecting the existence of such a composition. We are indebted to the

shrewd observations of Huber for a reconcilement of the Roman and the

French naturalists. The details which he has given of his discovery are

perhaps the most interesting in his delightful book.

"Soon," he says, "after some new combs had been finished in a hive,

manifest disorder and agitation prevailed among the bees. They seemed

to attack their own works. The primitive cells, whose structure we

had admired, were scarcely recognizable. Thick and massive walls,

heavy, shapeless pillars, were substituted for the slight partitions

previously built with such regularity. The substance had changed along

with the form, being composed apparently of wax and propolis. From

the perseverance of the workers in their devastation, we suspected

that they proposed some useful alteration of their edifices; and our

attention was directed to the cells least injured. Several were yet

untouched; but the bees soon rushed precipitately on them, destroyed

the tubes, broke down the wax, and threw all the fragments about.

But we remarked that the bottom of the cells of the first row were

spared; neither were the corresponding parts on both faces of the comb

demolished at the same time. The bees laboured at them alternately,

leaving some of the natural supports, otherwise the comb would have

fallen down, which was not their object: they wished, on the contrary,

to provide it a more solid base, and to secure its union to the vault

of the hive, with a substance whose adhesive properties infinitely

surpassed those of wax. The propolis employed on this occasion had

been deposited in a mass over a cleft of the hive, and had hardened

in drying, which probably rendered it more suitable for the purpose.

But the bees experienced some difficulty in making any impression on

it; and we thought, as also had appeared to M. de Réaumur, that they

softened it with the same frothy matter from the tongue which they use

to render wax more ductile.

"We very distinctly observed the bees mixing fragments of old wax with

the propolis, kneading the two substances together to incorporate

them; and the compound was employed in rebuilding the cells that had

been destroyed. But they did not now follow their ordinary rules of

architecture, for they were occupied by the solidity of their edifices

alone. Night intervening, suspended our observations, but next morning

confirmed what we had seen.

"We find, therefore, that there is an epoch in the labour of bees,

when the upper foundation of their combs is constructed simply of wax,

as Réaumur believed; and that, after all the requisite conditions

have been attained, it is converted to a mixture of wax and propolis,

as remarked by Pliny so many ages before us. Thus is the apparent

contradiction between these two great naturalists explained. But this

is not the utmost extent of the foresight of these insects. When they

have plenty of wax, they make their combs the full breadth of the hive,

and solder them to the glass or wooden sides, by structures more or

less approaching the form of cells, as circumstances admit. But should

the supply of wax fail before they have been able to give sufficient

diameter to the combs whose edges are rounded, large intervals remain

between them and the upright sides of the hive, and they are fixed

only at the top. Therefore, did not the bees provide against it, by

constructing great pieces of wax mixed with propolis, in the intervals,

they might be borne down by the weight of the honey. These pieces are

of irregular shape, strangely hollowed out, and their cavities void of

symmetry."[AY]

It is remarked by the lively Abbé la Pluche, that the foundations of

our houses sink with the earth on which they are built, the walls

begin to stoop by degrees, they nod with age, and bend from their

perpendicular;--lodgers damage everything, and time is continually

introducing some new decay. The mansions of the bees, on the contrary,

grow stronger the oftener they change inhabitants. Every bee-grub,

before its metamorphosis into a nymph, fastens its skin to the

partitions of its cell, but in such a manner as to make it correspond

with the lines of the angle, and without in the least disturbing the

regularity of the figure. During summer, accordingly, the same lodging

may serve for three or four grubs in succession; and in the ensuing

season it may accommodate an equal number. Each grub never fails to

fortify the panels of its chamber by arraying them with its spoils,

and the contiguous cells receive a similar augmentation from its

brethren.[AZ] Réaumur found as many as seven or eight of these skins

spread over one another: so that all the cells being incrusted with six

or seven coverings, well dried and cemented with propolis, the whole

fabric daily acquires a new degree of solidity.

It is obvious, however, that by a repetition of this process the cell

might be rendered too contracted; but in such a case the bees know well

how to proceed, by turning the cells to other uses, such as magazines

for bee-bread and honey. It has been remarked, however, that in the

hive of a new swarm, during the months of July and August, there are

fewer small bees or nurse-bees than in one that has been tenanted four

or five years. The workers, indeed, clean out the cell the moment that

a young bee leaves its cocoon, but they never detach the silky film

which it has previously spun on the walls of its cell. But though honey

is deposited after the young leave the cells, the reverse also happens;

and accordingly, when bees are bred in contracted cells, they are by

necessity smaller, and constitute, in fact, the important class of

nurse-bees.

We are not disposed, however, to go quite so far as an American

periodical writer, who says, "Thus we see that the contraction of

the cell may diminish the size of a bee, _even to the extinction of

life_, just as the contraction of a Chinese shoe reduces the foot even

to uselessness."[BA] We know, on the contrary, that the queen-bee

will not deposit eggs in a cell either too small or too large for the

proper rearing of the young. In the case of large cells, M. Huber took

advantage of a queen that was busy depositing the eggs of workers to

remove all the common cells adapted for their reception, and left only

the larger cells appropriated for males. As this was done in June, when

bees are most active, he expected that they would have immediately

repaired the breaches he had made; but to his great surprise they did

not make the slightest movement for that purpose. In the meanwhile the

queen, being oppressed by her eggs, was obliged to drop them about at

random, preferring this to depositing them in the male cells, which she

knew to be too large. At length she did deposit six eggs in the large

cells, which were hatched as usual three days after. The nurse-bees,

however, seemed to be aware that they could not be reared there, and

though they supplied them with food, did not attend to them regularly.

M. Huber found that they had been all removed from the cells during the

night, and the business both of laying and nursing was at a complete

stand for twelve days, when he supplied them again with a comb of small

cells, which the queen almost immediately filled with eggs, and in some

cells she laid five or six.

[Illustration]

[The accompanying illustration exhibits these three kinds of bees,

namely, the Queen, the Drone, and the Worker, together with the cells

which they respectively inhabit. Fig. 1 shows the queen-bee as she

appears when in command of a hive. When she first issues from the

royal cell, she is much smaller in the body, and an inexperienced

observer might have some difficulty in distinguishing her from an

ordinary worker. But any one who has been accustomed to bees can pick

her out as soon as his eyes rest upon her. Her body is rather larger

and narrower than those of the workers, and the wings are shorter in

proportion, slightly crossing at the tips when she is at rest. Fig. 2

represents the common worker-bee, which, as has already been mentioned,

is simply an undeveloped female. Fig. 3 is the male or drone-bee, which

is easily distinguishable, even by a novice. He is larger, stouter,

and heavier built than the female; his eyes are so enormous that they

seem to occupy nearly the entire head, and he has some well-defined

tufts of hair on the end of the abdomen. He can even be detected by

the ear, as he flies, the deep droning hum being quite unlike the

fussy, business-like sound produced by the worker. Fig. 4 represents

one of the royal cells, a little reduced in size. In making this cell,

the bees lose sight of their habitual economy of wax, and use enough

material for fifty ordinary cells. It is probable that the great size

of the cell enables the inclosed insect to expand, and so to be capable

of becoming the mother as well as the ruler of her subjects. The royal

cell is always placed at the edge of a comb, so as not to interfere

with the other cells, which contain honey, bee-bread, and grubs; and

in each hive there are generally several of these cells in different

stages of structure. Figs. 5 and 6 represent the proportionate sizes of

the cells which contain the drone and worker bees.]

* * * * *

The architecture of the hive, which we have thus detailed, is that of

bees receiving the aid of human care, and having external coverings of

a convenient form, prepared for their reception. In this country bees

are not found in a wild state; though it is not uncommon for swarms

to stray from their proprietors. But these stray swarms do not spread

colonies through our woods, as they are said to do in America. In the

remoter parts of that continent there are no wild bees. They precede

civilization; and thus when the Indians observe a swarm they say, "The

white man is coming." There is evidence of bees having abounded in

these islands, in the earlier periods of our history; and Ireland is

particularly mentioned by the Venerable Bede as being "rich in milk and

honey."[BB] The hive-bee has formed an object of economical culture in

Europe at least for two thousand years; and Varro describes the sort of

hives used in his time, 1870 years ago. We are not aware, however, that

it is now to be found wild in the milder clime of Southern Europe, any

more than it is in our own island.

The wild bees of Palestine principally hived in rocks. "He made him,"

says Moses, "to suck honey out of the rock."[BC] "With honey out of

the rock," says the Psalmist, "should I have satisfied thee."[BD] In

the caves of Salsette and Elephanta, at the present day, they hive in

the clefts of the rocks, and the recesses among the fissures, in such

numbers as to become very troublesome to visitors. Their nests hang in

innumerable clusters.[BE]

We are told of a little black stingless bee found in the island of

Guadaloupe, which hives in hollow trees or in the cavities of rocks by

the sea-side, and lays "up honey in cells about the size and shape

of pigeons' eggs. These cells are of a black or deep-violet colour,

and so joined together as to leave no space between them. They hang

in clusters almost like a bunch of grapes."[BF] The following are

mentioned by Lindley as indigenous to Brazil. "On an excursion towards

Upper Tapagippe," says he, "and skirting the dreary woods which extend

to the interior, I observed the trees more loaded with bees' nests than

even in the neighbourhood of Porto Seguro. They consist of a ponderous

shell of clay, cemented similarly to martins' nests, swelling from

high trees about a foot thick, and forming an oval mass full two feet

in diameter. When broken, the wax is arranged as in our hives, and the

honey abundant."[BG]

Captain Basil Hall found in South America the hive of a honey-bee very

different from the Brazilian, but nearly allied to, if not the same as,

that of Guadaloupe. "The hive we saw opened," he says, "was only partly

filled, which enabled us to see the economy of the interior to more

advantage. The honey is not contained in the elegant hexagonal cells of

our hives, but in wax bags, not quite so large as an egg. These bags or

bladders are hung round the sides of the hive, and appear about half

full; the quantity being probably just as great as the strength of the

wax will bear without tearing. Those near the bottom, being better

supported, are more filled than the upper ones. In the centre of the

lower part of the hive we observed an irregularly-shaped mass of comb,

furnished with cells like those of our bees, all containing young ones

in such an advanced state, that, when we broke the comb, and let them

out, they flew merrily away."

Clavigero, in his 'History of Mexico,' evidently describing the same

species of bee, says it abounds in Yucatan, and makes the honey of

Estabentum, the finest in the world, and which is taken every two

months. He mentioned another species of bee, smaller in size, and also

without a sting, which forms its nest of the shape of a sugar-loaf, and

as large or larger. These are suspended from trees, particularly from

the oak, and are much more populous than our common hives.

Wild honey-bees of some species appear also to abound in Africa. Mr.

Park, in his second volume of travels, tells us that some of his

associates imprudently attempted to rob a numerous hive of its honey,

when the exasperated bees, rushing out to defend their property,

attacked their assailants with great fury, and quickly compelled the

whole company to fly.

At the Cape of Good Hope the bees themselves must be less formidable,

or more easily managed, as their hives are sought for with avidity.

Nature has there provided man with a singular and very efficient

assistant in a bird, most appropriately named the honey-guide

(_Indicator major_, Veillot; _Cuculus indicator_, Latham). The

honey-guide, it is said, so far from being alarmed at the presence of

man, appears anxious to court his acquaintance, and flits from tree

to tree with an expressive note of invitation, the meaning of which

is both well known to the colonists and the Hottentots. A person thus

invited by the honey-guide seldom refuses to follow it onward till

it stops, as it is certain to do, at some hollow tree containing a

bee-hive, usually well stored with honey and wax. It may be that

the bird finds itself inadequate to the attack of a legion of bees,

or to penetrate into the interior of the hive, and is thence led to

invite an agent more powerful than itself. The person invited, indeed,

always leaves the bird a share of the spoil, as it would be considered

sacrilege to rob it of its due, or in any way to injure so sacred a

bird.

Useful, however, as is the honey-guide, it must always be carefully

watched, and the traveller must not follow it without keeping his eyes

well open. For although, as a general fact, the bird will lead its

followers to honey, it has a strange habit of leading them to the spot

where lies hidden some dangerous animal. Sometimes it brings them to

a rhinoceros, wallowing in a mud pool. Sometimes it directs them to

a solitary buffalo, one of the most dangerous animals that Southern

Africa produces, and one which the natives fear but little less than

the lion itself. And more than once the too-confiding traveller has

followed the honey-guide, and been led to a spot where was lying one of

the venomous serpents.

The Americans, who have not the African honey-guide, employ several

well-known methods to track bees to their hives. One of the most

common though ingenious modes is to place a piece of bee-bread on a

flat surface, a tile for instance, surrounding it with a circle of wet

white paint. The bee, whose habit it is always to alight on the edge

of any plane, has to travel through the paint to reach the bee-bread.

When, therefore, she flies off, the observer can track her by the

white on her body. The same operation is repeated at another place,

at some distance from the first, and at right angles to the bee-line

just ascertained. The position of the hive is easily determined, for it

lies in the angle made by the intersection of the bee-lines. Another

method is described in the 'Philosophical Transactions for 1721.' The

bee-hunter decoys, by a bait of honey, some of the bees into his trap,

and when he has secured as many as he judges will suit his purpose,

he encloses one in a tube, and, letting it fly, marks its course by

a pocket-compass. Departing to some distance, he liberates another,

observes its course, and in this manner determines the position of the

hive, upon the principle already detailed. These methods of bee-hunting

depend upon the insect's habit of always flying in a right line to its

home. Those who have read Cooper's tale of the 'Prairie' must well

remember the character of the bee-hunter, and the expression of "lining

a bee to its hive."

In reading these and similar accounts of the bees of distant parts of

the world, we must not conclude that the descriptions refer to the

same species as the common honey-bee. There are numerous species of

social bees, which, while they differ in many circumstances, agree in

the practice of storing up honey, in the same way as we have numerous

species of the mason-bee and of the humble-bee.

_CHAPTER VII._

CARPENTRY OF TREE-HOPPERS AND SAW-FLIES.

The operations of an insect in boring into a leaf or a bud to form

a lodgment for its eggs appear very simple. The tools, however, by

which these effects are performed are very complicated and curious.

In the case of gall-flies (_Cynips_), the operation itself is not so

remarkable as its subsequent chemical effects. These effects are so

different from any others that may be classed under the head of Insect

Architecture, that we shall reserve them for the latter part of this

volume, although, with reference to the use of galls, the protection

of eggs and larvæ, they ought to find a place here. We shall, however,

at present confine ourselves to those which simply excavate a nest,

without producing a tumour.

The first of these insects which we shall mention is celebrated for

its song, by the ancient Greek poets, under the name of _Tettix_.

The Romans called it _Cicada_, which we sometimes, but erroneously,

translate "grasshopper;" for the grasshoppers belong to an entirely

different order of insects. We shall, therefore, take the liberty of

calling the Cicadæ _Tree-hoppers_, to which the cuckoo-spit insect

(_Tettigonia spumaria_, Oliv.) is allied; but there is only one of the

true Cicadæ hitherto ascertained to be British, namely, the _Cicada

hæmatodes_ (Linn.), which was discovered in the New Forest, Hampshire,

by Mr. Daniel Bydder.

M. Réaumur was exceedingly anxious to study the economy of these

insects; but they not being indigenous in the neighbourhood of Paris,

he commissioned his friends to send him some from more southern

latitudes, and he procured in this way specimens not only from the

South of France and from Italy, but also from Egypt. From these

specimens he has given the best account of them yet published; for

though, as he tells us, he had never had the pleasure of seeing one

of them alive, the most interesting parts of their structure can be

studied as well in dead as in living specimens. We ourselves possess

several specimens from New Holland, upon which we have verified some of

the more interesting observations of Réaumur.

Virgil tells us that in his time "the cicadæ burst the very shrubs

with their querulous music;"[BH] but we may well suppose that he was

altogether unacquainted with the singular instrument by means of which

they can, not poetically, but actually, cut grooves in the branches

they select for depositing their eggs. It is the male, as in the case

of birds, which fills the woods with his song; while the female, though

mute, is no less interesting to the naturalist on account of her

curious ovipositor. This instrument, like all those with which insects

are furnished by nature for cutting, notching, or piercing, is composed

of a horny substance, and is also considerably larger than the size of

the tree-hopper would proportionally indicate. It can on this account

be partially examined without a microscope, being, in some of the

larger species, no less than five lines[BI] in length.

The ovipositor, or auger (_tarière_), as Réaumur calls it, is lodged in

a sheath which lies in a groove of the terminating ring of the belly.

It requires only a very slight pressure to cause the instrument to

protrude from its sheath, when it appears to the naked eye to be of

equal thickness throughout, except at the point, where it is somewhat

enlarged and angular, and on both sides finely indented with teeth. A

more minute examination of the sheath demonstrates that it is composed

of two horny pieces slightly curved, and ending in the form of an

elongated spoon, the concave part of which is adapted to receive the

convex end of the ovipositor.

When the protruded instrument is further examined with a microscope,

the denticulations, nine in number on each side, appear strong, and

arranged with great symmetry, increasing in fineness towards the point,

where there are three or four very small ones, beside the nine that

are more obvious. The magnifier also shows that the instrument itself,

which appeared simple to the naked eye, is, in fact, composed of three

different pieces; two exterior armed with the teeth before mentioned,

denominated by Réaumur files (_limes_), and another pointed like a

lancet, and not denticulated. The denticulated pieces, moreover, are

capable of being moved forwards and backwards, while the centre one

remains stationary; and as this motion is effected by pressing a pin

or the blade of a knife over the muscles on either side at the origin

of the ovipositor, it may be presumed that those muscles are destined

for producing similar movements when the insect requires them. By means

of a finely-pointed pin carefully introduced between the pieces, and

pushed very gently downwards, they may be, with no great difficulty,

separated in their whole extent.

The contrivance by which those three pieces are held united, while at

the same time the two files can be easily put in motion, is similar

to those of our own mechanical inventions, with this difference, that

no human workman could construct an instrument of this description

so small, fine, exquisitely polished, and fitting so exactly. We

should have been apt to form the grooves in the central piece, whereas

they are scooped out in the handles of the files, and play upon two

projecting ridges in the central piece, by which means this is rendered

stronger. M. Réaumur discovered that the best manner of showing the

play of this extraordinary instrument is to cut it off with a pair of

scissors near its origin, and then, taking it between the thumb and

the finger at the point of section, work it gently to put the files in

motion.

Beside the muscles necessary for the movement of the files, the handle

of each is terminated by a curve of the same hard horny substance as

itself, which not only furnishes the muscles with a sort of lever, but

serves to press, as with a spring, the two files close to the central

piece, as is shown in the lower figure.

M. Pontedera, who studied the economy of the tree-hoppers with some

care, was anxious to see the insect itself make use of the ovipositor

in forming grooves in wood, but found that it was so shy and easily

alarmed, that it took to flight whenever he approached; a circumstance

of which Réaumur takes advantage, to soothe his regret that the insects

were not indigenous in his neighbourhood. But of their workmanship,

when completed, he had several specimens sent to him from Provence and

Languedoc by the Marquis de Caumont.

[Illustration: Ovipositors, with files, of Tree-hopper, magnified.]

[Illustration: Excavations for eggs of Tree-hopper, with the chip-lids

raised.]

The gall-flies, when about to deposit their eggs, select growing plants

and trees; but the tree-hoppers, on the contrary, make choice of dead,

dried branches, for the mother seems to be aware that moisture would

injure her progeny. The branch, commonly a small one, in which eggs

have been deposited, may be recognised by being covered with little

oblong elevations caused by small splinters of the wood, detached at

one end, but left fixed at the other, by the insect. These elevations

are for the most part in a line, rarely in a double line, nearly at

equal distances from each other, and form a lid to a cavity in the wood

about four lines in length, containing from four to ten eggs. It is to

be remarked that the insect always selects a branch of such dimensions

that it can get at the pith, not because the pith is more easily

bored, for it does not penetrate into it all, but to form a warm and

safe bed for the eggs. M. Pontedera says, that when the eggs have been

deposited, the insect closes the mouth of the hole with a gum capable

of protecting them from the weather; but M. Réaumur thinks this only a

fancy, as, out of a great number which he examined, he could discover

nothing of the kind. Neither is such a protection wanted; for the woody

splinters above mentioned furnish a very good covering.

The grubs hatch from these eggs (of which, M. Pontedera says, one

female will deposit from five to seven hundred), issue from the

same holes through which the eggs have been introduced, and betake

themselves to the ground to feed on the roots of plants. They are not

transformed into chrysalides, but into active nymphs, remarkable for

their fore limbs, which are thick, strong, and furnished with prongs

for digging; and when we are told, by Dr. Le Ferve, that they make

their way easily into hard stiff clay, to the depth of two or three

feet, we perceive how necessary to them such a conformation must be.

Saw-flies.

An instrument for cutting grooves in wood, still more ingeniously

contrived than that of the tree-hopper, was first observed by

Vallisnieri, an eminent Italian naturalist, in a four-winged fly, most

appropriately denominated by M. Réaumur the _saw-fly_ (_Tenthredo_) of

which many sorts are indigenous to Great Britain. The grubs from which

these flies originate are indeed but too well known, as they frequently

strip our rose, gooseberry, raspberry, and red currant trees of their

leaves, and are no less destructive to birch, alder, and willows;

while turnips and wheat suffer still more seriously by their ravages.

These grubs may readily be distinguished from the caterpillars of

moths and butterflies by having from sixteen to twenty-eight feet, by

which they usually hang to the leaf they feed on, while they coil up

the hinder part of their body in a spiral ring. The perfect flies are

distinguished by four transparent wings; and some of the most common

have a flat body of a yellow or orange colour, while the head and

shoulders are black.

In order to see the ovipositor, to which we shall for the present turn

our chief attention, a female saw-fly must be taken, and her belly

gently pressed, when a narrow slit will be observed to open at some

distance from the apex, and a short, pointed, and somewhat curved body,

of a brown colour and horny substance, will be protruded. The curved

plates which form the sides of the slit are the termination of the

sheath, in which the instrument lies concealed till it is wanted by the

insect. The appearance of this instrument, however, and its singular

structure, cannot be well understood without the aid of a microscope.

[Illustration: _a_, Ovipositor of Saw-fly, protruded from its sheath,

magnified.]

The instrument thus brought into view is a very finely-contrived

saw, made of a horny substance, and adapted for penetrating branches

and other parts of plants where the eggs are to be deposited. The

ovipositor-saw of the insect is much more complicated than any of those

employed by our carpenters. The teeth of our saws are formed in a line,

but in such a manner as to cut in two lines parallel to, and at a

small distance from, each other. This is effected by slightly bending

the points of the alternate teeth right and left, so that one-half

of the whole teeth stand a little to the right, and the other half a

little to the left. The distance of the two parallel lines thus formed

is called the _course_ of the saw, and it is only the portion of wood

which lies in the course that is cut into sawdust by the action of the

instrument. It will follow that in proportion to the thinness of a saw

there will be the less destruction of wood which may be sawed. When

cabinet-makers have to divide valuable wood into very thin leaves, they

accordingly employ saws with a narrow course, while sawyers who cut

planks use one with a broad course. The ovipositor-saw being extremely

fine, does not require the teeth to diverge much; but from the manner

in which they operate, it is requisite that they should not stand,

like those of our saws, in a straight line. The greater portion of the

edge of the instrument, on the contrary, is towards the point somewhat

concave, similar to a scythe, while towards the base it becomes a

little convex, the whole edge being nearly the shape of an Italic _f_.

[Illustration: Ovipositor-saw of Saw-fly, with rasps shown in the cross

lines.]

The ovipositor-saw of the fly is put in motion in the same way as a

carpenter's hand-saw, supposing the tendons attached to its base to

form the handle, and the muscles which put it in motion to be the

hand of the carpenter. But the carpenter can only work one saw at a

time, whereas each of these flies is furnished with two, equal and

similar, which it works at the same time--one being advanced and the

other retracted alternately. The secret, indeed, of working more saws

than one at once is not unknown to our mechanics; for two or three are

sometimes fixed in the same frame. These, however, not only all move

upwards and downwards simultaneously, but cut the wood in different

places; while the two saws of the ovipositor work in the same cut,

and consequently, though the teeth are extremely fine, the effect is

similar to a saw with a wide set.

It is important, seeing that the ovipositor-saws are so fine, that they

be not bent or separated while in operation--and this, also, nature has

provided for, by lodging the backs of the saws in a groove, formed by

two membranous plates, similar to the structure of a clasp-knife. These

plates are thickest at the base, becoming gradually thinner as they

approach the point, which the form of the saws requires. According to

Vallisnieri, it is not the only use of this apparatus to form a back

for the saws, he having discovered, between the component membranes,

two canals, which he supposes are employed to conduct the eggs of the

insect into the grooves which it has hollowed out for them.

[Illustration: Portion of a Saw-Fly's comb-toothed rasp, and saw.]

The teeth of a carpenter's saw, it may be remarked, are simple, whereas

the teeth of the ovipositor-saw are themselves denticulated with fine

teeth. The latter, also, combines at the same time the properties of a

saw and of a rasp or file. So far as we are aware, these two properties

have, never been combined in any of the tools of our carpenters. The

rasping part of the ovipositor, however, is not constructed like our

rasps, with short teeth thickly studded together, but has teeth almost

as long as those of the saw, and placed contiguous to them, on the back

of the instrument, resembling in their form and setting the teeth of a

comb, as may be seen in the figure. Of course, such observations are

conducted with the aid of a microscope.

When a female saw-fly has selected the branch of a rose-tree, or any

other, in which to deposit her eggs, she may be seen bending the end

of her belly inwards, in form of a crescent, and protruding her saw,

at the same time, to penetrate the bark or wood. She maintains this

recurved position so long as she works in deepening the groove; but

when she has attained the depth required, she unbends her body into a

straight line, and in this position works upon the place lengthways, by

applying the saw more horizontally. When she has rendered the groove

as large as she wishes, the motion of the tendons ceases, and an egg

is placed in the cavity. The saw is then withdrawn into the sheath

for about two-thirds of its length, and at the same moment a sort of

frothy liquid, similar to a lather made with soap, is dropped over the

egg, either for the purpose of gluing it in its place or sheathing it

from the action of the juices of the tree. She proceeds in the same

manner in sawing out a second groove, and so on in succession, till she

has deposited all her eggs, sometimes to the number of twenty-four.

The grooves are usually placed in a line, at a small distance from

one another, on the same branch; but sometimes the mother-fly shifts

to another, or to a different part of the branch, when she is either

scared or finds it unsuitable. She commonly, also, takes more than one

day to the work, notwithstanding the superiority of her tools. Réaumur

has seen a saw-fly make six grooves in succession, which occupied her

about ten hours and a half.

The grooves, when finished, have externally little elevation above the

level of the bark, appearing like the puncture of a lancet in the human

skin; but in the course of a day or two the part becomes first brown

and then black, while it also becomes more and more elevated. This

increased elevation is not owing to the growth of the bark, the fibres

of which, indeed, have been destroyed by the ovipositor-saw, but to the

actual growth of the egg; for when a new-laid egg of the saw-fly is

compared with one which has been several days enclosed in the groove,

the latter will be found to be very considerably the larger. This

growth of the egg is contrary to the analogy observable in the eggs

of birds, and even of most other insects; but it has its advantages.

As it continues to increase, it raises the bark more and more, and

consequently widens, at the same time, the slit at the entrance; so

that, when the grub is hatched, it finds a passage ready for its exit.

The mother-fly seems to be aware of this growth of her eggs, for she

takes care to deposit them at such distances as may prevent their

disturbing one another by their development.

Another species of saw-fly, with a yellow body and deep violet-coloured

wings, which also selects the rose-tree, deposits her eggs in a

different manner. Instead of making a groove for each egg, like the

preceding, she forms a large single groove, sufficient for about two

dozen eggs. These eggs are all arranged in pairs, forming two straight

lines parallel to the sides of the branch. The eggs, however, though

thus deposited in a common groove, are carefully kept each in its

place; for a ridge of the wood is left to prevent those on the right

from touching those on the left--and not only so, but between each egg

of a row a thin partition of wood is left, forming a shallow cell.

[Illustration: Nest of eggs of Saw-fly, in rose-tree.]

The edges of this groove, it will be obvious, must be farther apart

than those which only contain a single egg, and, in fact, the whole is

open to inspection; but the eggs are kept from falling out, both by the

frothy glue before mentioned, and by the walls of the cells containing

them. They were observed also, by Vallisnieri, to increase in size like

the preceding.

[Illustration: _a a a_, Saw-fly of the gooseberry (_Nematus Ribesii_,

Stephens). _b_, its eggs on the nervures of a leaf. _d d_, the

caterpillars eating. _c_, one rolled up. _f_, one extended.]

[In the middle of summer, plenty of these grooves may be seen, by

looking at the under lid of leaf-stalks or delicate young twigs. Row

upon row of the grooves are sometimes found, so the all-destructive

power of the insects must indeed be great. The larvæ, when full fed,

dispose of themselves in various ways. Those of the gooseberry-fly, for

example (_Nematus Ribesii_), after they have stripped the bush of its

leaves, either seek the ground or remain on the branches, and spin a

series of cocoons, attaching them to each branch by their ends. Those,

therefore, who wish to destroy these little pests, must know both

localities of the cocoons, or they will allow one half to escape while

destroying the other.]

This insect has a flat yellow body and four pellucid wings, the two

outer ones marked with brown on the edge. In April it issues from the

pupa, which has lain under ground from the preceding September. The

female of the gooseberry saw-fly does not, like some of the family,

cut a groove in the branch to deposit her eggs;--"of what use, then,"

asks Réaumur, "is her ovipositor-saw?" In order to satisfy himself on

this point, he introduced a pair of the flies under a bell-glass along

with a branch bent from a red-currant bush, that he might watch the

process. The female immediately perambulated the leaves in search of

a place suited to her purpose, and passing under a leaf began to lay,

depositing six eggs within a quarter of an hour. Each time she placed

herself as if she wished to cut into the leaf with her saw; but, upon

taking out the leaf, the eggs appeared rather projecting than lodged

in its substance. The caterpillars are hatched in two or three weeks;

and they feed in company till after midsummer, frequently stripping

both the leaves and fruit of an extensive plantation. The caterpillar

has six legs and sixteen pro-legs, and is of a green colour mixed with

yellow, and covered with minute black dots raised like shagreen. In

its last skin it loses the black dots and becomes smooth and yellowish

white. The Caledonian Horticultural Society have published a number of

plans for destroying these caterpillars.

[Another remarkable mode of disposing of the pupa is shown in the

accompanying illustration; it represents the nest of an exotic saw-fly,

named _Deilocenes Ellisii_. In this instance, the numerous larvæ unite

in spinning for themselves a common envelope of considerable strength;

it is seen as it appears when attached to the branch of a tree. The

material of which it is composed is the tough silken fibre spun by

the larvæ of so many insects, which may be seen in perfection in the

cocoons of the Microgaster. Two species of this curious group will be

described in a future page.

By the side of the branch is seen a diagram of the same nest, as it

would appear in section. The irregularly angular cells are seen in the

centre, and around them is the common envelope composed of fibres.

As may be seen from the upper figure, as soon as the insects have

attained their perfect form, they gnaw their way out of the cell and

the covering also. The insect is shown as it appears when flying.

[Illustration]

We will conclude this chapter by a few remarks upon some exotic

insects, whose nests are not only remarkable in their form, but are

valuable to the entomologist in affording grounds for the reception

or rejection of certain familiar theories upon the subject of

this volume--Insect Architecture. Several of these nests are of

comparatively late discovery, and are therefore found in this work.

The curious series of cells shown in the left-hand figure is made by a

hymenopterous insect belonging to the genus Icaria, and the specimens

from which the drawing was taken may be seen in the British Museum.

They are made of a paper-like substance, much resembling in look the

material of which the common wasp builds its cells, but as they are

exposed to the air, they are necessarily tougher and stronger than

ordinary wasp cells, which are shielded from the elements. The insects

belonging to this genus make nests of very diverse forms, some of which

are stuck on leaves in a most curious manner, reminding the observer

of the parasitic mollercoids that cover the stems and fronds of large

seaweeds. Others, however, are not dependent upon leaves for their

support, but stand out boldly from the branches to which they are

fixed, supported entirely by a footstalk composed of the same material

as the cells, though necessarily of a harder and more compact substance.

[Illustration]

As many of these nests have been found in India, it is easy to trace

the manner in which they were made. The mother insect began by kneading

woody fibre into a paste, and making the footstalk of the future

nest. One end of this footstalk is attached very strongly to the

branch, and to the other end is fastened the first cell. As soon as the

Icaria has made the first beginning of the cell, and raised--or rather

lowered--the walls to a fourth or so of their complete dimensions, she

inserts an egg into the yet imperfect cell, and adds to the walls while

the egg is being hatched. Her next duty is, to add a second cell, and

this is quickly followed by a third, all these cells being fastened to

each other on three or four of their sides, leaving the others free and

unattached. It is evident that by this mode of construction the cells

nearest the branch must be the longest, because they are begun the

soonest, and this will always be found to be the case.

Now, there is a point respecting which the attention of the reader must

be specially solicited. On looking at the cells, he will see that they

are partly cylindrical and partly angular, and may perhaps think that

this fact goes towards proving that the hexagonal shape of bee cells is

owing to mutual pressure, the outer sides of the cells being rounded,

while the inner are angular. But, there are other cells in existence,

built by allied insects, and formed in an analogous manner, and which

are either angular or cylindrical, exactly according to the instinctive

powers of the insect which built them.

On the right hand of the Icarian nest may be seen a singular-looking

structure pendent at the end of a long footstalk. This is the nest of

an insect called _Mischocyttarus labiatus_, one of the Polistidæ. In

this case, the cells are built so as to be defended from the rain by a

sort of penthouse, over which all the rain-drops would run, and so fall

harmless to the ground. The cells of this insect are soft in texture,

and are more cylindrical than angular, the angles being but very

slightly marked.

Here, however, is the nest of an insect called _Raphigaster

Guiniensis_, which is built in a manner similar to that of the Icaria,

the cells being closely in contact with each other. The material of

which they are made is peculiarly soft. something like very thin and

flimsy grey paper. Consequently, they must press strongly upon each

other, and we might reasonably expect to find that their angles are

well and boldly developed. But, instead of that, we find that they have

no angles at all, but remain smooth and rounded throughout their length.

[Illustration]

Perhaps the most powerful argument against the equal pressure theory is

to be found in the nest of a species of Icaria, which is shown in the

accompanying illustration.

[Illustration]

As may be seen by reference to the illustration, the material of which

they are made is so soft, that they bend over by their own weight, and

therefore we might expect to find that they would follow the shape of

the Raphigaster and the Mischocyttarus. But, we find that all the

cells are boldly angular, and that the angles are just as sharp on the

exterior of each cell as on the sides which cement the cells together.

It is clear that the bold lines and decided angles of these cells

cannot have been produced mechanically, and that they must have been

intentionally formed by the insect architect.

One single cell, such as is here shown, is sufficient to overthrow

the theory of "equal pressure," by which insects were deprived of

all mechanical skill, and supposed to labour like so many animated

machines, without caring or knowing anything about the work on which

they were engaged. According to the equal pressure theory, each of

these cells would have required six similar cells around it before it

could have assumed the hexagonal form, and yet we find that a cell

which is only connected with its neighbour by one side, has its other

five sides angular, and with the angles boldly defined.]

_CHAPTER VIII._

LEAF-ROLLING CATERPILLARS.

The labours of those insect-architects, which we have endeavoured to

describe in the preceding pages, have been chiefly those of mothers to

form a secure nest for their eggs, and the young hatched from them,

during the first stage of their existence. But a much more numerous

and not less ingenious class of architects may be found among the

newly-hatched insects themselves, who, untaught by experience, and

altogether unassisted by previous example, manifest the most marvellous

skill in the construction of tents, houses, galleries, covert-ways,

fortifications, and even cities, not to speak of subterranean caverns

and subaqueous apartments, which no human art could rival.

The caterpillars, which are familiarly termed leaf-rollers, are perfect

hermits. Each lives in a cell, which it begins to construct almost

immediately after it is hatched; and the little structure is at once

a house which protects the caterpillar from its enemies, and a store

of food for its subsistence, while it remains shut up in its prison.

But the insect only devours the inner folds. The art which these

caterpillars exercise, although called into action but once, perhaps,

in their lives, is perfect. They accomplish their purpose with a

mechanical skill, which is remarkable for its simplicity and unerring

success. The art of rolling leaves into a secure and immovable cell

may not appear very difficult: nor would it be so if the caterpillars

had fingers, or any parts which were equivalent to those delicate and

admirable natural instruments with which man accomplishes his most

elaborate works. And yet the human fingers could not roll a rocket-case

of paper more regularly than the caterpillar rolls his house of leaves.

A leaf is not a very easy substance to roll. In some trees it is very

brittle. It has also a natural elasticity,--a disposition to spring

back if it be bent,--which is caused by the continuity of its threads,

or nervures. This elasticity is speedily overcome by the ingenuity

with which the caterpillar works; and the leaf is thus retained in its

artificial position for many weeks, under every variety of temperature.

We will examine, in detail, how these little leaf-rollers accomplish

their task.

One of the most common as well as the most simple fabrics constructed

by caterpillars, may be discovered during summer on almost every kind

of bush and tree. We shall take as examples those which are found on

the lilac and on the oak.

[Illustration: Lilac-tree Moth. (_Lozotænia riteana_, Stephens?)]

[Illustration: Nest of a Lilac-leaf Roller.]

A small but very pretty chocolate-coloured moth, abundant in every

garden, but not readily seen, from its frequently alighting on the

ground, which is so nearly of its own colour, deposits its eggs

on the leaves of the currant, the lilac, and of some other trees,

appropriating a leaf to each egg. As soon as the caterpillar is

hatched, it begins to secure itself from birds and predatory insects

by rolling up the lilac leaf into the form of a gallery, where it may

feed in safety. We have repeatedly seen one of them when just escaped

from the egg, and only a few lines long, fix several silk threads from

one edge of a leaf to the other, or from the edge to the mid-rib; then

going to the middle of the space, he shortened the threads by bending

them with his feet, and consequently pulled the edges of the leaves

into a circular form; and he retained them in that position by gluing

down each thread as he shortened it. In their younger state, those

caterpillars seldom roll more than a small portion of the leaf; but,

when farther advanced, they unite the two edges together in their whole

extent, with the exception of a small opening at one end, by which an

exit may be made in case of need.

[Illustration: Another nest of Lilac-leaf Roller.]

Another species of caterpillar, closely allied to this, rolls up the

lilac leaves in a different form, beginning at the end of a leaf, and

fixing and pulling its threads till it gets it nearly into the shape of

a scroll of parchment. To retain this form more securely, it is not

contented, like the former insect, with threads fixed on the inside of

the leaf; but has also recourse to a few cables which it weaves on the

outside.

[Illustration: Small green Oak-moth. (_Tortrix viridana._)]

[Illustration: Nests of Oak-leaf-rolling Caterpillars.]

Another species of moth, allied to the two preceding, is of a

pretty green colour, and lays its eggs upon the leaves of the oak.

This caterpillar folds them up in a similar manner, but with this

difference, that it works on the under surface of the leaf, pulling

the edge downwards and backwards, instead of forwards and upwards.

This species is very abundant, and may readily be found as soon as

the leaves expand. In June, when the perfect insect has appeared, by

beating a branch of an oak, a whole shower of these pretty green moths

may be shook into the air.

* * * * *

Among the leaf-rolling caterpillars, there is a small dark-brown

one, with a black head and six feet, very common in gardens, on the

currant-bush, or the leaves of the rose-tree (_Lozotænia rosana_,

Stephens). It is exceedingly destructive to the flower-buds. The eggs

are deposited in the summer, and probably also in the autumn or in

spring, in little oval or circular patches of a green colour. The grub

makes its appearance with the first opening of the leaves, of whose

structure in the half-expanded state it takes advantage to construct

its summer tent. It is not, like some of the other leaf-rollers,

contented with a single leaf, but weaves together as many as there

are in the bud where it may chance to have been hatched, binding

their discs so firmly with silk, that all the force of the ascending

sap, and the increasing growth of the leaves, cannot break through;

a farther expansion is of course prevented. The little inhabitant in

the meanwhile banquets securely on the partitions of its tent, eating

door-ways from one apartment into another, through which it can escape

in case of danger or disturbance.

The leaflets of the rose, it may be remarked, expand in nearly the same

manner as a fan, and the operations of this ingenious little insect

retain them in the form of a fan nearly shut. Sometimes, however, it is

not contented with one bundle of leaflets, but by means of its silken

cords unites all which spring from the same bud into a rain-proof

canopy, under the protection of which it can feast on the flower-bud,

and prevent it from ever blowing.

In the instance of the currant-leaves, the proceedings of the grub

are the same; but it cannot unite the plaits so smoothly as in the

case of the rose leaflets, and it requires more labour, also, as the

nervures, being stiff, demand a greater effort to bend them. When all

the exertions of the insect prove unavailing in its endeavours to

draw the edges of a leaf together, it bends them inwards as far as

it can, and weaves a close web of silk over the open space between.

This is well exemplified in one of the commonest of our leaf-rolling

caterpillars, which may be found as early as February on the leaves of

the nettle and the white archangel (_Lamium album_). It is of a light

dirty-green colour, spotted with black, and covered with a few hairs.

In its young state it confines itself to the bosom of a small leaf,

near the insertion of the leaf-stalk, partly bending the edges inwards,

and covering in the interval with a silken curtain. As this sort of

covering is not sufficient for concealment when the animal advances

in growth, it abandons the base of the leaf for the middle, where it

doubles up one side in a very secure and ingenious manner.

[Illustration: Nest of the Nettle-leaf-rolling Caterpillar.]

We have watched this little architect begin and finish his tent upon

a nettle in our study, the whole operation taking more than half an

hour. (J. R.) He began by walking over the plant in all directions,

examining the leaves severally, as if to ascertain which was best

fitted for his purpose by being pliable, and bending with the weight

of his body. Having found one to his mind, he placed himself along

the mid-rib, to the edge of which he secured himself firmly with the

pro-legs of his tail; then stretching his head to the edge of the

leaf, he fixed a series of parallel cables between it and the mid-rib,

with another series crossing these at an acute angle. The position in

which he worked was most remarkable, for he did not, as might have

been supposed, spin his cables with his face to the leaf, but throwing

himself on his back, which was turned towards the leaf, he hung with

his whole weight by his first-made cables. This, by drawing them into

the form of a curve, shortened them, and consequently pulled the edge

of the leaf down towards the mid-rib. The weight of his body was not,

however, the only power which he employed; for, using the terminal

pro-legs as a point of support, he exerted the whole muscles of his

body to shorten his threads, and pull down the edge of the leaf. When

he had drawn the threads as tight as he could, he held them till he

spun fresh ones of sufficient strength to retain the leaf in the bent

position into which he had pulled it. He then left the first series

to hang loose while he shortened the fresh-spun ones as before. This

process was continued till he had worked down about an inch and a half

of the leaf, as much as he deemed sufficient for his habitation. This

was the first part of the architecture.

By the time he had worked to the end of the fold, he had brought the

edge of the leaf to touch the mid-rib; but it was only held in this

position by a few of the last-spun threads, for all the first-spun

ones hung loose within. Apparently aware of this, the insect protruded

more than half of its body through the small aperture left at the end,

and spun several bundles of threads on the outside precisely similar

to those ropes of a tent which extend beyond the canvas, and are

pegged into the ground. Unwilling to trust the exposure of his whole

body on the outside, lest he should be seized by the first sand-wasp

(_odynerus_) or sparrow which might descry him, he now withdrew to

complete the internal portion of his dwelling, where the threads were

hanging loose and disorderly. For this purpose he turned his head

about, and proceeded precisely as he had done at the beginning of his

task, but taking care to spin his new threads so as to leave the loose

ones on the outside, and make his apartment smooth and neat. When he

again reached the opposite end, he constructed there also a similar

series of cables on the outside, and then withdrew to give some final

touches to the interior.

It is said by Kirby and Spence,[BJ] that when these leaf-rolling insects

find that the larger nervures of the leaves are so strong as to prevent

them from bending, they "weaken it by gnawing it here and there half

through." We have never observed the circumstance, though we have

witnessed the process in some hundreds of instances; and we doubt

the statement, from the careful survey which the insect makes of the

capabilities of the leaf before the operation is begun. If she found

upon examination that a leaf would not bend, she would reject it, as we

have often seen happen, and pass to another. (J. R.)

* * * * *