IMEMOmS OF THE NATIOIS'AL ACADEMY OF SCIENCES. 
161 
The prothoracic plate is leather broad, but quite short antero-posteriorly, with four piliferous 
warts on the front and lour on the hinder edge. The pililerous warts on the succeeding segments 
are large, distinct, black, and bear but a single hair. The tubercles on the second and third tlio- 
racic warts are arranged in a straight transverse row; the two dorsal ones are slightly larger than 
those on the third thoracic segment. On the abdomitial segments the lour dorsal tubercles are all 
of the same size and arranged in a trapezoid, which becomes longer, going backward to segment 7, 
On the eighth segment there is a double large black tubercle bearing two bristles; the tubercle is 
several times larger than any of the others, and is evidently the result of the coalescence of the 
homologues of the two dorsal warts occurring on the segments in front. The ninth segment with 
the four dorsal tubercles arranged in a square, with the lateral ones farther up on the back than 
the homologous ones in front, and in a subdorsal position. The suranal plate is black-brown, nearly 
three-fourths as long as broad, bearing six marginal and two dorsal median hairs. The thoracic 
legs are black: the abdominal legs pale, with an external dark chitinoiis plate above the planta. 
The general color of the body is glaucous green, being of the same hue as the color of the 
underside of the aspen leaf, on which it feeds. There is a brown dorsal spot on the eighth 
abdominal segment, on which the tubercle rests, while along the sides, low down, at the base of 
the abdominal legs, and in corresponding places where the legs are wanting, is a row of irregular 
reddish si)ots. The skin under a ^-inch objective is seen to be studded with line, dark, short, 
conical setm or granulations which ai'e largest and thickest on the sides of and at the base of the 
middle abdominal legs. The hairs over the body are glandular, slightly bulbous, and about half 
as long as the body is thick. 
The two tenant hairs on the thoracic feet are knife shaped, somewhat as in lehthyura indusiu 
The plantm of the abdominal legs have a much larger number of crochets than usual in larvie of 
Stage I, as there are twenty*six of them, forming a nearly complete but broken circle, and the 
ci’ochets themselves are rather short and blunt. 
Stage II. — Length, 8 mm. Molted August 3. The Pheosia characters are now declared, 
owing to the traustbrmation of the dorsal tubercle on the eighth abdominal segment into a lleshy 
cone or low horn. The larva feeds on the edge of the hole which it eats out of the leal’, and at first 
sight may be mistaken for a sawlly larva, owing to the dark reddish brown spots and band on 
the sides, which resemble abdominal legs aTul assimilate it in appearance to the edge of the hole, 
Avhich turns dark after it has been eaten out by the caterpillar. 
The lyrothoracic shield has now disa^ypeared. — The head slightly narrows above and is slightly 
bilobed, smooth, and shining, a little wider than the body, which narrows a little toward the end; 
it is a dark chestnut- brown on the sides, pale chestnut in front. The body is pale green above, 
still of the same hue as the underside of the leaf. The underside is peculiar in the thoracic and 
short, thick abdominal legs being dark livid brown; with a large chestnut-brown patch on the 
base of each, and on the first and second abdominal segments is a dark brown blotch where the 
base of the legs would be if they were present; farther along in the space between the fourth 
pair of legs and the anal legs is an irregular dark brown broad line extending along the side of 
the body to the sides ol' the anal legs. The latter are used in creeping, but are about half as 
large as the middle ones. 
The hump on the eighth abdominal segment is now tvcdl developed.^ high, conical, and Jleshg, 
slightly inclined haclcward, dark at tip, and still bearing two bristles, though the dark chitinous 
spine is obsolete; the horn-like tubercle is half as high as the segment is thick. The body behind 
the “ caudal horn ” narrows rather rapidly to the end of the suranal plate, which is larger than 
before, but pale and of the same color as the body. 
The anal legs are used, but are about half as large as the middle ones and with much fewer 
crochets, Avhich are very numerous in the middle legs, forming a nearly complete circle. The 
piliferous warts in general are now very much smaller and iialer than in Stage I, being green, like 
the body, and scarcely visible under a strong lens. The hairs are sparse, only one arising from 
a wart, and they are short and fine. 
In this stage the sub] )ro thoracic eversible gland was observed in an alcoholic specimen. It 
forms a large transverse sack, bleached white by the alcohol, and contrasting with the red skin 
of the side of the segment. It sends off two lateral siphon-like long and slender finger-shaped 
S. Mis. 50 11 
