POPLAR CATERPILLARS. 451 
Larva. — One- fourth inch long; light green, slender. Head large, round, slightly 
depressed medially; face pink, with a purplish tinge; extremity of the body dark 
sea-green, with a large wart or tubercle, pyramidal in form, upon which rests the 
horn. 
First molt.— One-half inch long; apple green, with a light yellow longitudinal 
stripe below the dorsal ridge; diagonal lines yellowish white; horn purple, straight, 
very short. 
Second molt. — Seven-eighths inch in length ; rich dark green, finely granulated, giv- 
ing it a beautiful velvety appearance ; thorax adorned with two transverse crests or 
collars, studded with fine points tipped with white. 
Third molt. — One and a quarter inches in length ; thickest medially K light green, 
otherwise unchanged. 
Fourth molt. — One and seven-eighths inches long ; light green, coarsely granulated, 
granules studded with fine white points, giving the skin a frosted appearance ; crests 
on the thorax much reduced in size. 
Fifth molt. — Three inches long ; £ inch in diameter ; hind crest lost, anterior one 
much reduced ; spiracles small, rust-red ; true legs brown ; prolegs brownish yellow ; 
horn lost, except a mere rudiment ; yellow longitudinal stripes very obscure. 
Pupa. — Two inches long; f in diameter ; dark chestnut brown ; cylindrical, hold- 
ing its size well to the sixth segment, thence tapering abruptly and ending in a point 
or thorn ; head obtuse, thoracic poriion round, not angular. 
Moth. — The largest species of the genus. Olive drab ; head very small, and with- 
out a prominent crest; antennae of the males transversely biciliated beneath. Fore- 
wings scalloped, with a transverse sinuous pale line near the base ; a whitish comma- 
shaped stigma on a broad undulated dark olive-colored central band, and two trans- 
verse undulated lines towards the tip ; under side purple in the middle of the disk. 
Hind wings purple in the middle and at base, with a transverse black spot, and an 
abbreviated dusky blue band near the anal angle. Body very robust, and with the 
legs immaculate. Expanse of wings, 5 inches. 
20. The io moth. 
Hyperchiria io Fabr. 
The gregarious caterpillars of this moth were observed on the aspen 
at Brunswick, Me., July 27; the young larvae, apparently just hatched, 
occurred July 16, forming a group on an aspen leaf. 
Young larva after hatching.— Stout, thick bodied; the body is uniformly pale red- 
dish brown, while the large branching spines are brown and black. Length, 5 to 
6 mm . 
Young larva 15 mm in length.— Body moderately thick, of the usual shape of the 
genus. Body pale reddish horn-colored, with six longitudinal paler lines ; four rows 
of dorsal and subdorsal black spinulated spines ; and also a similar lateral row (or 
six rows in all). Head blackish-brown. 
After molting, July 28.— Length, 17 to 18 mm . The spinules on the spines are mostly 
whitish (those at the ends black), giving a grayish appearance to the larva. Head 
reddish amber ; body, reddish-yellow. 
Larva after another molt, August 6.— Length, 30 to 35 mm . As soon as the old skin is 
cast, and while the parts are limp and soft, the spines present a curious appearance; 
the spinules being short, and placed close together, so that the whole spine forms an 
elongated conical mass. Soon the spinules stand out and the larva presents the 
normal appearance. It is now much lighter than before, all the spines being dense 
and pale, but afterwards they become wholly black or black at the ends, including 
the hairs, though the general effect of the mass of spines is to give a pale horn- 
colored yellowish-green hue to the body. Color of the body as before, but there is a 
L 
