346 



MUSEUM OF ANIMATED NATURE. 



[Insects. 



The figures and appearance of these eeRs "'" he 

 better understood by lelerence to our example* than 

 by mere verbal description. 



Fisj. 342r> represents the eges of four different 

 insects, all differing from each other in external 

 characters— they are of course greatly uiaenifted. 



Fig. ;i4.:G represent! the egg of a buttei-fly, and 

 of a moth, masnified. 



Fig. 3427 represents the eggs of several species 

 as they appear under a microscope: a, the egg of 

 Geometra armillata ; 6 of an unknown aquatic in- 

 sect ; f, of the lackey-moth; </, of a caddis-fly 

 (Fhryganea atrata^ : e, of the red-underwing moth ; 

 /, of the cabbage-butterfly (Pontia Brassiere) : </, of 

 the Clifton nonpareil-moth. 



Fig. 3428 represents : a, the egg of the Angle- 

 shades moth, compared with the case of an echinus 

 (Clypeaster). 



Fig. 342'J represents : n, the egg of the meadow 

 brown butterfly ; and b, the egg of the brimstone- 

 moth. 



Fig. 3430 represents : a, the dung-fly ; b and c, 

 the front and side views of its eegs, magnified ; d d, 

 several of these eggs deposited in cow-dung. 



Fig. 3431 represents the pedunculated eggs of the 

 lace-winged fly (Chrysopa reticulata), attached to 

 a sprig of lilac. The'mode in which these eggs are 

 attached is very simple. The female flv fixes a 

 minute drop of gluten to the branch, and clrawing it 

 out, as a spider does his line, to the requisite length 

 leaves the egg fixed secuiely on its summit. The 

 design in this singular plan of operation is to secure 

 the eggs from the attacks of the caterpillars, of lady 

 birds (Coccinellae), and other insects, the footstalk 

 being too smooth and slender for them to climb 

 upon. 



Jt is very common to hear of blighting winds, 

 that is, of winds carrying myriads of the eggs of 

 insects, and spreading them over gardens, orchards, 

 and fields, which the caterpillars devastate, strip- 

 ping the trees and bushes of their leaves. We doubt 

 very much the correctness of this theory, which 

 appears to have arisen from the supposed analogy 

 between these eggs and the seeds of many plants, 

 ■which are distributed by the wind, as those of the 

 dandelion, and various mosses and mould-plants. 

 See Fig. 3432, representing microscopic views of 

 apple and pear mould : A A, part of a withered 

 apple covered with mould ; an, a a, several of the 

 individual mould-plants, highly magnified ; b, a 

 branched one ; c, rf, seed vessels, one bursting and 

 scattering its contents ; e, one of a mushroom shape ; 

 f, a portion of pear-mould of a branched shape. 

 Insects carefully deposit their eggs, and in seasons 

 when myriads of a certain species swarm in gardens, 

 devouring the leaves of trees, the eggs have been 

 deposited in the spot where the spoilers are at work, 

 but have been unnoticed. Many plants project their 

 seed to a distance, as the sweet pea, and still more 

 so the minute fungus Sphserobolus stellatus, repre- 

 sented at Fig. 3433 : A, the natural size ; B, mag- 

 nified ; C, a sectional view, with the seed just pre- 

 vious to projection ; D, the seed in the act of pro- 

 jection ; E, a plant immediately after projection ; a, 

 the seed ; bb.a. line indicating its course. 



Various insects have been observed to project 

 their eggs to some distance, and an analogy has 

 been supposed to exist in this respect between them 

 and these plants. But we believe that it is only 

 under an influence of alarm, and when caught, that 

 this projection takes place : this is the ease with 

 the crane-fly when captured, and also of another 

 fly, called, by the Abbe Preaux, Mouche Baliste — 

 "insecte i, quatre ailes qui lance sesoeufsJidiverses 

 reprises, ct comme par un ressort lorsqu'on le saisit." 



All insects deposit their eggs upon or near the 

 substances which are to furnish the future cater- 

 pillars with food. Consequently situations chosen, 

 and the mode in which their safety is secured, are 

 almost as diversified as the species are numerous. 

 Some insects deposit their eggs on the leaves of 

 plants, some glue them to the bark, others lay them 

 on putrescent animal or vegetable substances, others 

 leave them in the water, and others prepare for 

 them artificial receptacles ; the living bodies of 

 other animals, and the substance of plants, afford a 

 nidus for the eggs of many. 



The rose-leaf roller (Logotasnia rosana) deposits 

 her eggs in oval groups, covered with a cement, 

 either "upon the branches of the rose-tree or upon 

 some smooth object adjacent. Each group contains 

 about fifty eggs ; the caterpillar appears in the 

 spring, and is well known as the " worm i' th' bud ;" 

 it mines into the yet unfolded blossom, where it be- 

 comes very fat, and ultimately rolls up the rose-leaf 

 forming a tent or dwelling in which to undergo its 

 transformation. Fig. 3434 shows two groups of eggs 

 of this species on a pane of glass. 



The lackey-motti (Clisiocampa neustria) glues 

 her eggs by means of a strong and hard cement to 

 the twigs of bushes, arranging them in an annular 

 manner, so that they form a ring or belt round the 

 twig ''see Fig. 3435). Another species of moth, not 



ascertained, arranges her eggs in an eleaant spiral 

 manner round a twig, covering them with a coat of 

 fine short down (see Fig. 343U). 



Another species, the gipsey-moth (Hypogymna 

 dispar), like the rabbit and eider-duck, strip« the 

 down from oflf the hinder parts of her own body, in 

 order to make a soft envelope for her eggs, in thtJ 

 form of a cone. Placing herself with the head 

 downwards, on the trunk of an oak or elm, she first 

 arranges a little bed of this down, into which she 

 thrusts an egg; this is covered with gluten, which 

 not only secures a covering of the soft material, but 

 renders the egg adherent to the bark of the tree. 

 PrOjpeeding in the same manner, she continues for 

 several hours adding to the mass, and then rests, 

 returning the next day to her labours. The work is 

 then completed, and the whole is covered externally 

 with a thatch of haii-s, arranged so as to throw off 

 the winter rains. 



Fig. 34.37 shows : a the female gipsy-moth, one- 

 third of the natural size, just finishing her group of 

 eggs ; b, a female with the body covered with down ; 

 c, a circle of eggs covered with hair ; d, a conical 

 mound of eggs covered up with hair. 



Fig. .3438 represents the lackey-moth in all its 

 stages : a, the belt of eggs ; b, the caterpillar ; c, the 

 pupa in its cocoon, within a folded leaf; d, the 

 moth. 



Among the insects which entrust their eggs to 

 the water we may notice the gnat (Culex pipiens), 

 her operations being remarkably curious and inter- 

 esting. The larva of the gnat is aquatic, and 

 abounds during the summer in all stagnant waters; 

 but were the eggs to be submerged, their vitality 

 would infallibly be destroyed. The gnat, therefore, 

 in order to keep them afloat, has recourse, instinct- 

 guided, to a wonderful plan. She forms them into 

 a raft, which floats, exposed to the action of the 

 sun and air, essential to the development of the 

 larvffi. 



At the time of laying her eggs the female gnat 

 rests upon a twig or stone, her body being level 

 with the surface of the water, which it touches. 

 Extending her hind limbs, and using them with 

 great adroitness, she proceeds to glue egg after egg 

 together, fixing them side by side, to the number of 

 two or three hundred. In this manner she forms a 

 long concave raft, pointed at each end, and which is 

 remarkable for buoyancy and the property of throw- 

 ing ofi^ the water. Each individual egg is of a 

 compress oval form, pointed above and covered 

 with a glutinous fluid. The under apex is valvular, 

 a lid opening for the exit of the larva into the water, 

 which takes place in the course of a few days. 



Fig. 3439 represents two gnats forming their raft 

 of eggs ; a represents the commencement of the 

 raft; i, the raft about two-thirds completed; c, a 

 perfect boat resting on the surface of the water. 



Fig. 3440 is a magnified representation of a raft 

 of gnats' eggs. 



The eggs of the gnat are not singular in having 

 a valve or lid for the exit of the larva, which opens 

 by being pushed. The eggs of those disgusting 

 parasites, the pediculus humanus, and the nirmus, 

 which infests the neck-feathers of the golden phea- 

 sant, are valvular, as is also the egg of the field-bug 

 Pentatoma (see Fig. 3441) : a, the egg of the Pedi- 

 culus humanus ; b, egg of Pentatoma ; c, the ribbed 

 egg of a species of moth, which, after the escape of 

 the caterpillar, exhibits an opening, the ribs having 

 expanded for its exit. 



A common species of moth, the vapourer (Orgygia 

 antiqua), of which the female has only the mere 

 rudiments of wings, and is of course incapable of 

 flight, or indeed of moving far from the spot in which 

 her last metamorphosis took place, has recourse to 

 an admirable expedient for preserving her eggs 

 through the winter. She fixes them on the substance 

 of the silken cocoon from which she has herself 

 emerged, and which is always in some snug and shel- 

 tered situation. " Thus," says Swammerdam, " like 

 a prudent housewife, she never leaves her habita- 

 tion." Her existence however is brief, for, the great 

 object of her being accomplished, she soon perishes. 



Fig. 3442 shows the wingless female and the male 

 of the vapourer, with the eggs upon the cocoon from 

 which the female has issued. 



The eggs of this moth, as we have said, and of 

 many others, have to pass the winter, and by a wise 

 provision they are capable of enduring, without loss 

 of vitality, a far greater degree of cold than they are 

 ever naturally exposed to, even during the most 

 severe winters. 



In the year 1709, when Fahrenheit's thermometer 

 fell to 1", and animals and plants suffered most ex- 

 tensively, yet, as Boerhaave observes, this intense 

 severity did not destroy the eggs of insects, not even 

 those exposed to its influence in the open fields, on 

 the naked earth, or the branches of trees. When 

 the spring had tempered the air, these eggs pro- 

 duced as they usually did after the mildest win- 

 ters. During December, 1788, the cold was in 

 France even more intense, yet the eggs of insects 



were not destroyed. Spallanzani, relating his ex- 

 periments on the eggs of insects, says, " I have 

 exposed eggs to a more rigorous trial than the 

 winter of 1709. Those of several insects, and 

 among them the silk-worm moth, the elm butterfly, 

 were enclosed in a glass vessel, and buried five hours 

 in a mixture of ice and rock-salt ; the theimometer 

 fell G' below zero. In the middle of the following 

 spring, however, caterpillars came from all the eggs, 

 and at the same time as those that had suffered no 

 extraordinary cold. In the following year I submit- 

 ted them to an experiment still more hazardous. A 

 mixture of ice and nitrate of ammonia reduced the 

 thermometer 22° below zero, that is, 23° lower than 

 the cold of 1709. They were not injured, as I had 

 evident proof by their being hatched." In these 

 instances the eggs remain unfrozen, resisting bv a 

 vital law, little understood, the effects of cold, which 

 would have infallibly destroyed either the caterpil- 

 lars or perfect insects. This does not only apply to 

 the eggs of insects ; but of birds also, except that 

 those of the latter are not capable of enduring so low 

 a temperature as those of the former : yet the resist- 

 ance of the vital piinciple to the influence of cold is 

 considerable, but when that principle is destroyed 

 the cold easily operates. The celebrated John Hun- 

 ter found that he could freeze an egg at the cold of 

 zero, and that after thawing it, its vitality being de- 

 stroyed, it would freeze when exposed to the same 

 degree of cold sooner by seven and a half minutes. 

 A new-laid egg took an hour to freeze in 15° and 

 17°, but when thawed it froze in 25° in half the time. 

 To suppose, then, that rigorous winters destroy the 

 eggs of insects, and thereby diminish their numbers, 

 is fallacious ; on the contrary, it often happens that 

 after a severe season they are more than ordinarily 

 numerous, perhaps because the cold has affected 

 the beings which feed upon them, either destroying 

 them, rendering them torpid, or driving them to 

 more temperate quarters. 



With respect to the effects of heat, the resistance 

 of the eggs of insects is almost as great as in the in- 

 stance of cold. Spallanzani found that, though silk- 

 worms perished when exposed to a temperature of 

 108° of Fahrenheit, the eggs did not entirely cease 

 to be fertile till the temperature amounted to 144°. 

 In the case of the blow-fly, a great many of the eggs 

 produced maggots at 124°, but at 135° and 138° most 

 were destroyed, and all at l40°. 



Many insects make elaborate structures for pro- 

 tecting their eggs and brood, over which they watch 

 with assiduous care, supplying the wants of the latter 

 with unceasing industry. We may mention the bee, 

 the wasp, and the ant. There are, however, other 

 examples. The termite builds large and solid struc- 

 tures, in which she deposits her countless eggs ; these 

 the labouring community take under their charge, 

 and remove from one compartment to another, as the 

 weather may render necessary. Fig. 3443 .shows 

 the cell of a queen of the Termites bellicosus broken 

 open in front : the labourers are seen surrounding the 

 queen, and carrying ofther eggs for safety. To these 

 insects we shall again have to advert. 



There are various species of insects, called mason- 

 \^'asps, mason-bees, mining-bees, &c., which, unlike 

 the hive-bees and common wasps, are solitary, but 

 which form receptacles for their eggs, requiring no 

 little labour and perseverance. That delicate little 

 bird the sand-martin (Hirundo riparia) bores deep 

 galleries in the face of sandy cliffs, with its short but 

 strong bill, for the purpose of nidification ; and in 

 some of these insects the same plan is carried into 

 execution. A common species of solitary mason- 

 wasp (Odynerus), see Fig. 3444, is capable of making 

 its way into the substance of a brick, by means of its 

 powerful jaws ; it detaches fragment after fragment, 

 severing pieces of the size of a mustard-seed, with 

 which the insect flies away, carrying them to a dis- 

 tance from the scene of her labours, lest they should , 

 indicate to the sharp eyes of the ichneumon-fly or 

 cuckoo-fly (Tachina larvarum) the " whereabouts" 

 of her cell. Fig. 3445 shows the mandibles of the 

 mason-wasp greatly magnified. Mr. Rennie in- 

 forms us that he saw one of these wasps busy in ex- 

 cavating a hole in one of the hard bricks of the wall 

 of a house at Lee, in Kent, and had already made 

 considerable advance in her labours with her strong 

 mandibles ; she severed fragment after fragment, 

 carrying each away, and in two days finished her 

 cell, the entrance of which just admitted her body. 

 When the excavation was completed, it took two 

 days more to line it with a coating of clay, to deposit 

 the eggs, and, as he supposes, imprison a few pa- 

 ralyzed spiders or caterpillars for the larvte to feed 

 upon. The entrance was then closed up with a 

 thick layer of clay. In November the observer 

 hewed away the brick around the nest, and found 

 the excavation to be rather less than an inch in 

 depth ; it appeared, moreover, that, notwithstanding 

 all her care, the wasp had not been able to prevent 

 the entrance of the cuckoo-fly, Tachina (see Fig. 

 3446), which had deposited an egg there, and the 

 grub hatched from it had devoured one of the wasp- 



