84 Studies on Life-history of Bombycine Moths. 



weeks. In 1890 a larva in stage IV w^as observed feeding on grass 

 June 22d, and two days later a full-fed caterpillar was found ; they 

 were observed more frequently a week or two later, but the last 

 fully-fed caterpillar was seen July 27th. The first appearance of 

 the moths in 1890 was July 13th, when three males entered the 

 window in the night attracted by the light, and males appeared 

 sooner and were afterwards much more numerous than the females. 

 Confining a number of both sexes eggs were laid July 27th to 28th, 

 and these hatched August 8th to 10th, so that the duration of the 

 egg or embryo state is between ten or eleven days and two weeks. 



Ugg. — Length 0.8 mm. or a little less than a millimeter. The 

 egg is regularly hemispherical in shape (not spherical, as stated in 

 1864), slightly higher than broad. Under a Tolles triplet of high 

 power the shell is seen to be very finely, minutely pitted, but under 

 a low power appears to be smooth and shining. Under a Tolles 

 ^-inch objective the surface of the shell is seen to be divided into 

 very minute quite regular polygonal areas, bounded by a slight 

 ridge ; from this ridge on one side of the area project horizontally 

 across the middle of the area one, or more usuall}' two very delicate 

 slender tapering hair-like processes nearly reaching the opposite side 

 of the polygon. 



The eggs are deep yellow when laid, remaining so till the embryo 

 forms, when they are dark ash-colored, darkest above. 



Larva, stage T. — Hatched August 8th to 10th. Length 2.5 mm. 

 Head black, smooth, shining, and rather broader than the body. 

 The body tapers slightly to the end; it is at first light yellowish, 

 afterwards becoming darker. In the older, darker ones the body is 

 pale flesh-color, as usual in Arctians. The prothoracic shield is 

 moderately large, being antero-posteriorly quite short, but rather 

 broad, sublunoid ; it bears on its front edge four piliferous warts, 

 all of nearly the same size, and each bearincr a single hair, which is 

 fine, tapering, like those on all the rest of the body, there being 

 apparently in the Zygaenidoe, as in the Arctians, no bulbous glandu- 

 lar hairs. There are no piliferous warts or hairs on the hinder edge 

 of the shield. On each of the two other thoracic segm.ents there 

 are but two large dorsal flattened piliferous warts, which are oval, 

 each bearing three long black hairs, the longest being about twice 

 as long as the body is thick. 



Abdominal segments 1 to 8, with four dorsal flattened piliferous 

 warts, each bearing a single hair, arranged in an obscurely marked 



