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 moJt.— 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, 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; J 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 ; fin 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 portion round, not angular. 



Moth. — The largest species of the genus. Olive drab ; head very small, and with- 

 out a prominent crest; antennse 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 larvre, 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 



gmm^ 



Young larva 15™™ 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, Jidy 28. — Length, 17 to 18™™. 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™™. 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 aa 

 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 efi^ect 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 



