INSECT. 



colour undergone by the latter being visible through 

 the slender coating of the egg. 



In many species the eggs are deposited singly; in 

 >thers, however, they are discharged en masse, of 

 #hich latter, the most remarkable instance occurs in 

 ihe cock roaches (Blatlee), of which we have already 

 given an account. Others again arrange them sym- 

 metrically (as in the cylindrical pointed eggs of the 

 Semblis lutea, fig. 6), and others enclose them in a mass 

 of gluten, especially those species which inhabit the 

 water in the larva state; many species employ a 

 gummy matter to attach them firmly to the substances 

 on which they are placed ; whilst some (as the yellow- 

 tail moth, Arctia chryxorrhced) wraj) them in a coat- 

 ing of down (fig. 7), which they pull off their own 

 bodies by the assistance ot an apparatus fitted for 

 that purpose ; and the lackey motl (Lasiocampa 

 Neiutria) deposits her eggs in a spiral coil round the 

 stems of fruit-trees (fig. 8). 



The period which elapses between the deposition 

 of the egg and the birth of the larva depends upon 

 the temperature of the atmosphere, as well as upon 

 the species of insect. Thus, whilst the early laid 

 eggs of the tortoise-shell butterfly hatch in a few 

 days, those which are not laid till autumn will not 

 produce caterpillars until spring. The eggs of the 

 meatfly hatch in a very few days, or even hours ; 

 eight days are required by the eggs of the painted 

 lady butterfly ; whilst the caterpillars of the machaon 

 butterfly are not hatched under a month. It is, how- 

 ever, a general rule, that those eggs which are depo- 

 sited in the autumn are not hatched until the fol 1 ^ r'n? 

 spring. 



The investigation of the development of the grub 

 whilst inclosed within the egg is attended with so 

 much difficulty, owing to the minuteness of the ob- 

 jects, that hitherto but little progress has been made 

 in this branch of the subject. Dr. Herold, however, 

 whose admirable microscopic observations we have 

 already noticed, has taken it up ; and the first part of 

 his magnificent work entitled " Disquisitiones Ani- 

 njalium Vertebris carentihus in ovo Formatione," has 

 recently appeared, and will tend to throw nvich light 

 upon this intricate subject. One peculiarity ought 

 not to be omitted relative to this part of our subject, 

 namely, that the eggs of the sawflies, gallflies, and 

 ants, increase very considerably in their size, and 

 alter in form previous to the exclusion of the larva, 

 and which is doubtless owing to the membranous 

 covering of the egg and to the growth of the inclosed 

 larvjE. In general, the embiyo cateipillar is observed 

 coiled up within the egg, the head being brought into 

 contact with the tail. 



We have said that the majority of insects die pre- 

 vious to the birth of their progeny, but this is not the 

 case with the whole. Thus De Geer ascertained 

 that a large species of field-bug (Pentatoma grisea) 

 survives this event, and that she leads her brood 

 about, consisting of from thirty to forty young ones, 

 in the same way as a hen does her chickens. Some- 



what similar ooservations have been made upon the 

 common earwig by De Geer, as well as by the author 

 of" Insect Transformations," who has published the 

 following interesting notice in the Penny Magazine : 

 " About the end of March I found an earwig brood- 

 ing over her eggs in a small cell scooped out in a 

 garden border, and in order to observe her proceed- 

 ings, I removed the eggs into my study, placing 

 them upon fresh earth under a bell-glass. The care- 

 ful mother soon scooped out a fresh cell, and collected 

 the scattered eggs with great care to the little nest, 

 placing herself over them, not so much, as it after- 

 wards appeared, to keep them warm, as to prevent 

 the too rapid evaporation of their moisture. When 

 the earth began to dry up she dug the cell gradually 

 deeper, till at length she got almost out of view ; and 

 whenever the interior became too dry, she withdrew 

 the eggs from the cell altogether, and placed them 

 round the rim of the glass, where some of the eva- 

 porated moisture had condensed : upon observing 

 this, I dropped some water into the abandoned cell, 

 and the mother soon afterwards replaced her eggs 

 there. When the water which had dropped had 

 nearly evaporated, I moistened the outside of the 

 earth opposite the bottom of the cell, and the mother 

 perceiving this, actually dug a gallery right through 

 to the spot where she found the best supply of mois- 

 ture. Having neglected to moisten the earth for 

 some days, it again became dry, and there was none 

 even round the rim of the glass as before. Under 

 these circumstances, the mother earwig found a little 

 remaining moisture quite under the clod of earth, 

 upon the board of the mantel-piece, and thither she 

 forthwith carried her eggs. The subsequent pro- 

 ceedings were not less interesting; for though I 

 carefully moistened the earth everyday, she regularly 

 changed the situation of the eggs morning and even- 

 ing, placing them in the original cell at night, and on 

 the board under the clod during the day, as if she 

 understood the evaporation to be so great when the 

 sun was up, that her eggs might be left too dry before 

 night. I regret to add, that during my absence the 

 glass had been moved and the mother escaped, having 

 carried away all her eggs but one or two, which soon 

 shrivelled up." De Geer was more fortunate, and as 

 we have ourselves repeatedly observed, noticed the 

 care of the female in defending her young when 

 hatched. 



There are other insects whose attention is devoted 

 to the care of the eggs and the education of the 

 young, especially in the social species. When the 

 period is arrived for the hatching of the egg, the 

 enclosed larva bursts through the envelope, either by 

 main force or by gnawing through it with its jaws 

 Sometimes, however, one end of the egg is provided 

 with a sort of cap, which is easily pushed open. 



T/ie Larva. The insect has now arrived at an 

 active state of existence ; it is now that it is destined, 

 in a more especial manner, to grow and to eat. It is to 

 this state that the ordinary terms caterpillar, grub, and 

 maggot are generally applied in a manner so inde- 

 finitely, that it is impossible, with any pretension to 

 correctness, to assign these terms to any precise 

 divisions of insects. In general, insects at this period 

 of their lives appear in the form of a cylindrical 

 ringed and fleshy worm, provided generally with a 

 distinct head and six scaly legs attached to the ante- 

 rior part of the body. The head, however, in some 

 species is not distinct, and the legs are sometimes 



