Butterfly.—The club of the antennæ is not very heavy, hooked, the hooked portion about as long as the rest of the club. The palpi are directed forward, with the second joint heavily scaled, and the third joint very small. The fore wing may be with or without the costal fold in the male sex. The cut gives a correct idea of the neuration. The hind wing is evenly rounded on the outer margin, sometimes slightly angled at the extremity of the submedian vein.
[a]Fig. 155.]—Neuration of the genus Thorybes.
Egg.—The egg is subglobular, somewhat flattened at the base and on top, marked with numerous fine and not much elevated longitudinal ridges. The micropyle covers the upper surface of the egg and is not depressed.
Caterpillar.—The caterpillar somewhat resembles that of the genus Epargvreus, but is relatively shorter, the head proportionately larger and more globular. The neck is greatly strangulated.
Chrysalis.—The chrysalis is somewhat curved in outline, with a strongly hooked cremaster and a prominent projection on the back of the thoracic region.
(1) Thorybes pylades, Scudder, Plate XLVIII, Fig. 6, ♁; Plate II, Figs. 25, 29, larva; Plate VI, Fig. 28, chrysalis (The Northern Dusky-wing).
Butterfly.—The upper side is represented correctly in Plate XLVIII. On the under side the wings are dark brown, shading into hoary-gray on the outer margins. The hind wings are crossed by irregular basal, median, and postmedian brown bands of darker spots, shaded with deeper brown internally. The translucent spots of the upper side reappear on the lower side of the fore wings. Expanse, 1.60 inch.
Early Stages.—These are elaborately described in the pages of Dr. Scudder's great work. The caterpillar feeds on clover, Lespedeza, and Desmodium.
This insect is found throughout the United States and Canada, but is not as yet reported from the central masses of the Rocky Mountain region. It probably, however, occurs there also in suitable locations. It is very common in New England.