THE STATE ENTOMOLOGIST. 149 



them hang instead of holding them upright, as they did while they were 

 young. By the end of July they have become full grown, when they 

 present the appearance of Figure 84, f. The worm on being pulled 

 out, appearing as at Figure 84, a. This full grown condition is not 

 ined, however, without critical periods. At four different times 

 ig their growth these worms close up the mouths of their 



. for two days to cast their skins or moult, as is the nature of 

 their 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 

 tssage of the excrement. 

 During their growth they are very slow travelers and seldom 

 the tree on which they were born, but when full grown they 

 become quite restless, and it is at this time that they do all their trav- 

 eling, dropping on to persons by their silken threads and crossing the 

 sidewalks in all directions. A wise instinct urges them to do this, for 

 did they remain on one tree, they would soon multiply beyond the 

 r of that tree to sustain them, -nd 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. A strange instinct leads them to 

 fasten their cocoons to the twigs only of the trees they inhabit, 

 so that these cocoons will remain secure through the winter, and not 

 to the leaf-stalk where they would be blown down with the leaf.* Af- 

 ter thus fastening; their bags, they line them with a good thickness of 

 the same material, and resting awhile from their labors, at last cast 

 skins and become chrysalids. Hitherto the worms had all been 

 alike, but now the sexes are distinguishable, the male chrysalis (Fig. 

 84, b) being but half the size of the female chryalis (shown inside of 

 the bag at e). Three weeks afterwards a still greater change takes 

 pla^e, the sexes differentiating still more. The male chysalis works' him- 

 self down to the end of his bag and, hanging half-way out, the skin bursts 

 he moth (Fig. 84, d) with a black body and glassy wings escapes, 

 and when his wings are dry, soars through the air to seek his mate. — 

 She never leaves her case, but issues from her chrysalis in the 

 shape of an abortive, footless and wingless affair (Fig. 84, e) and 

 after copulating, works herself back into the chrysalis skin, fills its 

 upper but posterior end with eggs and stops up the other end with 

 little there is left of her body when she gets through. These 

 eggs which are quite soft and yellowish, pass the winter protected in 

 the bags, and produce young worms again the following spring, 

 which go through the same cycle of transformations thus hurriedly 

 described. 



This insect is essentially polyphagous, for it occurs alike on ever- 



: l have noticed that the Ailaatbus tree is almost entirely exempt from the attacks of this 

 worm, but cannot yet tell whether iSaie is beeause the leaves are repulsive to it, or whether, the 

 »iag compound, the worm's instinct fails it, ia that it fastens its case to the mid-stalk, 

 which falls and carries the case with it to the ground. I incliae to the latter belief however, from 

 t that the insect is such a general feeder, and that a few isolated cases are sometimes seen at- 

 tached event" wing tbat they can feed and. mature on this tree. 



