264 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



of the foiirtb, fifth, sixth, and seventh dorsal joints, while from each side of the head 

 arises a long plnme-like tuft of black hair projecting forward and outward. A simi- 

 lar plume projects upwards from the last dorsal joint. The hairs composing these 

 plumes are coarse, barbed, knobbed, and arranged in sets of unequal length, thus 

 giving the plumes a turbinate appearance. 



Pupation. — Six days after the third molt a portion of the larvje spin up: all these 

 produce male moths. The female caterpillars, which up to this time have been undis- 

 tinguishable from the male caterpillars, undergo a fourth (and, as it appears from 

 more recent experience, in some instances even a fifth) molt and acquire twice the 

 size of the male caterpillar. This last, when full grown, measures about twenty 

 millimeters in length. The cocoon spun by the male caterpillar is of whitish or yel- 

 lowish color and sufficiently thin to show the insect within. It consists of two layers, 

 the hairs of the tufts and brushes of the caterpillar being interwoven with the outer 

 layer. The female cocoon is correspondingly larger, of gray color, and much more 

 solid and denser than the male cocoon. The male chrysalis (Fig. 13 d), which is soon 

 formed within the cocoon, is of brownish color, sometimes whitish on the ventral 

 side, and covered on the back and sides with fine white hairs. The female chrysalis 

 (Fig. 102 c) is much larger than the male, and otherwise differs, especially in lacking 

 the wing-sheaths and in having on the three first segments after the head transverse 

 flattened protuberances composed of scales, which are much less visible in the male. 

 The duration of the j)upa state is less than a fortnight. 



The imago. — The male (Fig 102 e) is a winged moth with feathery antennae and very 

 hairy forelegs. The general color is ashy-gray, the front wings being crossed by un- 

 dulated bands of darker shade, with two black markings on the outer edge near the 

 tip and a white spot on the inner edge also near the tip. He may frequently be seen 

 sitting on the trunks of trees or on the shady side of houses, etc., as he rests during 

 the day and flies only after dusk, often being attracted by light. The female (Fig. 

 102 a) is totally different from the male in appearance and resembles a hairy worm 

 rather than a moth, since she possesses the merest rudiments of wings. She is of a 

 pale gray color, the antennie being short and not feathered, the legs rather slender 

 and not covered with long hairs. She has consequently no power of flight, and is 

 barely able to walk. After working her way out of the chrysalis and cocoon she 

 takes her place on the outside of the latter, and patiently awaits the approach of the 

 male. Here she also deposits and protects her eggs in the manner already mentioned, 

 after which she drops exhausted to the ground and perishes. The white mass cover- 

 ing the eggs is at first viscous, but soon dries, becoming brittle, and is impervious 

 to water. 



Hibernation. — The species hibernates normally in the egg state, but occasionally a 

 living chrysalis may be found in winter-time. On January 30, 1874, we received 

 from Mr. Hunter Nicholson, from Knoxville, Tenu., a newly-hatched female, and this 

 had, no doubt, prematurely issued from a hibernating chrysalis. This is, however, 

 quite exceptional, and the different climatic conditions to which the species is sub- 

 jected in its wide distribution do not seem to alter the normal mode of hibernation. 



Nimiber of annual generations, — In the latitude of Washington the species is two- 

 brooded, the imagos of the first generation appearing in the first part of June, those 

 of the second generation in September and October. On several occasions we have 

 found, however, that a portion of the caterpillars from one and the same batch of 

 eggs would be feeding while the rest had already transformed to imagos. The result 

 of this retardation and irregularity in development is that caterpillars may be found 

 continuously throughout the season from June till October, and that there is, conse- 

 quently, no distinct dividing line between the two generations. In the more northern 

 States the species is single-brooded, the caterpillars appearing in the months of July 

 and August. 



Natural enemies and parasites. — The fact that the caterpillar makes no effort to 

 conceal itself shows that it enjoys immunity from enemies, and notably from birds. 



