Genus Thanaos 



Early Stages. — Unknown. 



Alpbeus occurs in Nevada, Arizona, and New Mexico. 



There are four other species of the genus found in our fauna. 



Genus THANAOS, Boisduval 

 (The Dusky-wings) 



Butterfly. — The antennze have a moderately large club, curved, 

 bluntly pointed. The palpi are porrect, the third joint almost 

 concealed in the dense hairy vestiture of the second joint. The 

 neuration of the wings is represented in the cut. 

 The fore wing in the case of the male always has a 

 costal fold. The butterflies comprised in this genus 

 are all, without exception, dark in color, in a few 

 species having bright spots upon the hind wings. 

 The genus reaches its largest development in 

 North America. The discrimination of the various 

 species is somewhat difficult. 

 Fig. 160.— Egg. —The egg is somewhat like the egg in the 

 Neuration of the genus Achalarus, but the micropyle at the upper 

 end of the egg is relatively larger and not as deeply 

 depressed below the surface. The sides are ornamented, as in 

 Achalarus, by raised vertical ridges, between which are numerous 

 cross-ridges; in a few cases the vertical ridges arebeaded, or marked 

 by a series of minute globose prominences, upon the edge. 



Caterpillar.- — The caterpillars are cylindrical, tapering from 

 the middle forward and backward, marked with lateral and dor- 

 sal stripes, with the neck less strangulated than in the preceding 

 genera. 



Chrysalis. — Not greatly differing in outline from the chrysalis 

 of the preceding genera, in most species having the outline of the 

 dorsum straight on the abdominal segments, with the thoracic 

 segments forming a slight hump or elevation; convex on the ven- 

 tral side, the cremaster being usually well developed. 



(1) Thanaos brizo, Boisduval and Leconte, Plate XLV, Fig. 

 7, § ; Plate VI, Fig. 38, chrysalis (The Sleepy Dusky-wing). 



Butterfly. — The band of postmedian spots on the fore wing 

 is composed of annular dark markings, is regular, crosses the 

 wing from the costa to the hind margin, and is reproduced on 



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