THE AMERICAN ENTOMOLOGIST. 



145 



When the web is finished, the insect, emits a 

 yellow tluid with which it besmears the inside 

 of the cocoon, and thns etTectiially conceals 

 itself from view. (See Fig. 97, rf). This species 

 remains in the chrysalis state about twenty 

 days. Some kinds of moths pass all the fall, 

 winter and spring months, that is, three-quarters 

 of the year, in this state. Some of these are 

 enclosed in cocoons of such dense texture that 

 the inner surface I'esembles glazed parchment, 

 and would seem to be almost impervious to the 

 atmosphere. This has given rise to the ques- 

 tion whether insects in the pupa state cannot 

 live without air, as well a« without food. 

 Some experiments performed with the chrysa- 

 lids of the Tent Caterpillar go to disprove this 

 notion. A number of cocoons were moistened 

 witli oil so as to exclude the air; in every in- 

 stance the enclosed pnpa perished without com- 

 pleting its transformation. The nicety and 

 compactness with which the parts of an insect 

 are folded up in its pupal envelope is, indeed, 

 wonderful. No effort of human ingennity could 

 replace it there, after it has once emerged. 

 Goldsmith, in his entertaining but fanciful work 

 upon Animated Nature, asserts that ins-ects of 

 this kind, when they have emerged from the 

 pupal covering, expand their wings so rapidly 

 that the eye can scarcely attend their unfolding. 

 This is very improbable, in any case, and in the 

 species now before us, as I have often witnessed, 

 the expansion of the wings is very slow and 

 gradual, and yet steadily progressive, so that 

 the time occupied in the operation does not 

 nsually exceed fifteen minutes. 



[Fig. OS] 



The American Tjackey moth, when fnlly de- 

 veloped, measures about one inch and a half 

 from tip to tip of the expanded wings. It is 

 nsually of a ])ale brick color, but individuals are 

 occasionally seen much darker, or of an ashy- 

 brown color. Across the fore wings are two 

 straight, oblique whitish lines. The antenna; 

 are moderately pectinate, or feather-like, in the 

 male, and very slightly so in the female. The 

 hollow tongue, or sucker, through which insects 

 of this order imbibe their nutriment, is wholly 

 wanting in tliis species, as, indeed, it is gener- 

 ally in the particular group to which it belongs. 

 Of course they take no food, and live bnt a short 



time. A number of these moths wliich were 

 put into a box immediately after they had come 

 from their cocoons, were alive on the third day, 

 but were all dead on the fourth. Their short 

 lives have but one object — the pairing of the 

 sexes and the deposition of the eg^s by the 

 female, for a future generation. The following 

 experiment illustrates some of their habits: 

 Three female moths were enclosed in a glass 

 vessel. They were quiet during the day, but 

 became very restless as night approached, show- 

 ing that like the moths in general, they arc 

 nocturnal in their habits. On the third day a 

 twig of apple tree was introduced into the 

 vessel. The moths immediately ran up upon it, 

 and put themselves in position for laying their 

 eggs. This was accomplislied in the following 

 manner. Placing herself transversely upon the 

 side of the twig, she curved her abdomen under 

 the twig and extended it up the opposite side 

 as far as slie could reach, and commenced de- 

 positing her eggs, one after another, gradually 

 withdrawing the abdomen till she liad laid a 

 row of eggs across the underside of the twig. 

 She then, in the same manner, deposited another 

 row, parallel to aud in contact with the first. 

 Owing to their nnnatural situation, or the ab- 

 sence of the opposite sex. or to some unknown 

 cause, these moths in confinement succeeded in 

 laying but two or three rows of eggs, whilst in 

 a state of nature they lay from fifteen to tvventv 

 rows, containing in all an average of about two 

 hundred and fifty eggs. They subsequently 

 cover the eggs with a coating of brown varnish 

 which etiectually protects them from the vicis- 

 situdes of the weather. In no case, however 

 warm or protracted the autumn may be, do 

 these eggs ever liatch till the following s])rino-. 

 So that the Tent Caterpillar, unlike nntny of 

 our noxious insects, never has but one brood 

 in the season. How is it that these little germs 

 of being remain insensible to the heats of July, 

 August and September, and yet burst into 

 vitality at almost the first touch of spring? We 

 know that if the young caterpillars came out 

 in the fall, they would perish from inability to 

 eat the tough autumnal foliage. But what 

 natural law can we conceive ot, that exercises 

 such a discretionary power? 



Again, by what subtle and inscrutable instinct 

 does the parent insect select those trees which 

 are suitable for the deposition of her eggs, 

 whatever may be their size, shape, or situation? 

 How does this poor insect, of three days' dura- 

 tion, know that her future progeny can thrive 

 upon the foliage of the Apple and the Cherry, 

 whilst it would perish upon that of the Oak (>r 



