36 



THE AMERICAN ENTOMOLOGIST. 



attached by the anterior legs, with their tails 

 hoisted in the air, they each spin around them- 

 selves a ring of silk, to which they soon fasten 

 bits of leaf. They continue adding to the lower 

 edge of the ring, pnshiug it up as it increases in 

 depth, till it reaches the tail, and forms a sort 

 of cone, as represented in Figure 28, g. As 

 the worms grow, they continue to increase their 

 bags from the bottom, until the latter become 

 so large and heavy that the worms allow them 

 to hang, instead of holding them upright, as 

 they did while they were 3'oung. By the end of 

 July, the worms acquire their full growth, when 

 they present the appearance of Figure 28, /. 

 At this stage, on being pulled out of its bag or 

 follicle, the worm appears as at Figure 28, a, 

 that portion of the body which is alwaj^s covered 

 by the bag, being soft, and of a dull, smoky 

 brown, inclining to reddish at the sides; while 

 the three anterior, or thoracic segments, which 

 are exposed when the insect is feeding or march- 

 ing, are horny, and mottled with black and 

 white. The prolegs, on the hidden part of the 

 body are but poorly developed, and consist of but 

 slight wart-like projections; they are furnished, 

 however, with numerous small hooks, which 

 answer an admirable purjjose, in enabling the 

 bearer to cling to his home-spun coat, which 

 shelters him from the weather, and defends him 

 from his enemies, and which is even more essen- 

 tial to his existence than are the clothes we wear 

 to ours. The worms do not arrive at their full- 

 grown condition without passing through criti- 

 cal periods. At four different times during their 

 growth they close up the mouths of their bags, 

 and retire for two days to cast tlieir skins or 

 moult, as is the nature of tlieir kind, and they 

 push their old skins through a passage which 

 is always left open at the extremity of the bag, 

 and which also allows the passing of the excre- 

 ment. 



During their growth they are very slow trav- 

 elers, and seldom leave the tree on which they 

 were born ; but when full grown they become 

 quite restless ; and it is at this time that they 

 wander by the day, dropping on to persons by 

 their silken threads, and crossing the sidewalks 

 of our cities in all directions. It is from this 

 habit of dropping on to persons that they have 

 been called "Drop-worms." A wise instinct 

 urges them to thus wander from place to place, 

 for, did they remain on one tree, they would 

 soon multiply beyond the power of that tree to 

 sustain them, and would in consequence become 

 extinct. When they have lost their migratory 

 desires, they fasten their bags very securely by 

 a strong band of silk to the twigs of the tree on 



which they happen to be. Here again, a 

 strange instinct leads them to thus fasten their 

 cocoons to the twigs only of the tree they 

 inhabit, so that these cocoons will remain 

 through the winter; and not to the leaf-stalk, 

 where they would be blown down with the 

 leaf. After thus fastening their bags, the)^ line 

 them with a good thickness of soft white silk, 

 and after turning around in the bag so as 

 to have the head towards the lower orifice, they 

 rest awhile from their labors, and at last cast 

 their skins and become chrysalids. Hitherto 

 the worms had all been alike in appearance, but 

 now the sexes are distinguishable, the male 

 chrysalis (Fig 28, 6) being but half the size of 

 that of the female, and exhibiting the encased 

 wings, legs and antennas as in all ordinary 

 chrysalids, while hers shows no signs of any 

 such members. (See inside of bag.at e). Three 

 weeks afterwards a still greater change takes 

 place the sexes differentiating still more. The 

 male chrysalis Avorks himself down to the end of 

 his bag, and, hanging half-way out, the skin 

 bursts, and the moth (Fig. 28, d,) with a black 

 body and glassy wings, escapes, and, when his 

 wings are dry, soars through the air to seek his 

 mate, who is not blessed with wings, but is an 

 abortive affair with the head and general ap- 

 pearance of the larva, but still more degraded, 

 since she has not even the legs which it pos- 

 sessed: she is in fact a naked yellowish bag of 

 eggs, with a ring of soft light brown silky hair 

 near the tail. (See Fig. 28, c). 



Dr. Harris wrote to Edward Doubleday, on 

 the 29th of October, 1849,* as follows: 



"The males are disclosed in September and 

 the early part of October, and immediately 

 afterwards the females will be found to be im- 

 pregnated. I examined about fifty female folli- 

 cles on the 25th of October, and found all the 

 females escaped, and their puparia half full of 

 fertilized eggs. It is not true that the females 

 remain in their puparia or in their follicles. 

 Among all those examined as above mentioned, 

 not a single female was discovered; they had 

 come out of their pupa skins, and had also left 

 their follicles. It is only at an early ijeriod, or 

 in some rare cases when the females have re- 

 mained unimpregnated till this time, that any 

 females are to be found within tlieir pupa skins. 

 But they do not leave their pupa skins until 

 they have been impregnated, and have laid their 

 eggs. 



"How the male contrives to get at the female 

 is a mystery that I have not yet solved. The 

 pupa sidn of the female splits in the middle of 

 the little carinated ridge found on the top and 

 fore part of the thorax, and also laterally, so as 

 to admit of a kind of T-shaped opening. It is 

 through this that the male organ must be intro- 



•Eiitoniolopical CoiTespondenoe^ p. 173. 



