Dec, 1904.] Dyar : Poison Ivy Caterpillars. 249- 



Class I, HEXAPODA. 



Order V, LEPIDOPTERA. 



POISON IVY CATERPILLARS. 



By Harrison G. Dyar, A. M., Ph.D., 

 Washington, D. C. 



Two similar Pyralid larvae may be found on poison ivy leaves, liv- 

 ing solitary in a loose open web, by which the leaves are more or less 

 folded or united. They rest in the web, not on the leaf, and are con- 

 spicuous by their bright colors. Both were known to the late Dr. C. 

 V. Riley, though I do not find that he ever published descriptions of 

 them. He confused the two species, as is evidenced by his giving them 

 both the same number. One of them, perhaps both, were seen by the 

 late Dr. Geo. D. Hulst, and he refers to one in a very brief and in- 

 adequate manner (Ent. Amer., v. 52, 1889). Last summer at Week- 

 apaug, R. I., I found poison ivy very abundant and had the oppor- 

 tunity to observe both species. I made the following notes : 



Epipaschia superantalis Clemens. 



Eggs. — Elliptical, flat like the eggs of Cochlidiidas, laid singly or in small groups 

 a little overlapping, i X -6 mm. in size. Opaque pale yellowish, with a narrow clear 

 rim ; surface dull, densely coarsely reticulate with rounded raised lines, appearing 

 somewhat granular. On the next day the embryos had developed and the eggs were 

 suffused with pinkish-red. Hatched in nine days. 



Stage I. — Head held flatly, whitish with a smoky brown band on the sides con- 

 tinuing the lateral line of the body and a mark bordering the clypeus. Body slender, 

 straight, whitish colorless, distinct subdorsal and lateral vinous brown lines running 

 the whole length, narrow, sharp. Feet normal, concolorless, the anal ones lined by 

 the lateral stripe. The subdorsal line is elliptically remote on joint 2. The larvae sat 

 on the back of a leaf on a loose web, free of the leaf and lying parallel to the veins. 



Stage II. — Head greenish -luteous, a black band on each side and an abbreviated 

 v-mark over the clypeus; width .4 mm. Body slender, greenish, greener dorsally ; 

 a broad black-brown lateral band composed of the subdorsal and lateral lines being 

 joined by an interpolated lateral line. Anal feet reddish lined, outstretched ; other 

 feet pale. 



Staxe III — Head .6 mm., as before, white with black marks. The anal feet 

 are black lined above. 



Stage IV. — Head white over the clypeus and a dot at the apex of each lobe, the 

 rest black; width 1. 05 mm. Body yellow dorsally, with traces of a dark dorsal line 

 intersegmentally ; sides black, enclosing the narrow white lines that divide the black 



