212 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



him it usually rests on the ground with the wings fully expanded, 

 touching the earth behind, but considerably elevated in front. When 

 it is sipping the moisture from the surface the antennae droop at 

 an angle of about 30° with the body. When it alights on a twig 

 the wings are generally placed at about right angles with each other 

 and the antennae then diverge at an angle of about 110° ; but its 

 wings are soon fully expanded, as on the ground, and then the an- 

 tennae approach until they are at about right angles with each other. 

 One may sometimes see them alight with expanded wings in the 

 bright sunlight and then, as if it were too hot for them, raise all 

 the wings equally until they are edgewise to the sun, or with the 

 slightest possible divergence, the fore wings dropped a little so that 

 the costal margin is entirely vertical. 



There is a partial second brood of this butterfly in August, but 

 this appears to consist of few individuals. 



The caterpillar feeds on species of willow and of poplar. 



THANAOS MARTIALIS (Scudder) 



Plate 52, Figures 10 to 12 



Occurr^ence. — Mr. Shoemaker has this butterfly from the District 

 taken early in spring, and I have it from Cabin John, May 4 and 11, 

 1930, and from near Great Falls, June 17, 1923. Mr. Schonborn's 

 specimens are dated April 20 and 29. 



Remarks. — This species is found both in the woods and in open 

 fields in the vicinity of woods. There are two broods, the second 

 brood, in which the individuals are not so numerous as in the first, 

 appearing about the middle of July. Mr. Lintner- says that the but- 

 terflies of the second brood are more subdued in color than those of 

 the first. 



THANAOS JUVENALIS (Fabricius) 

 Plate 51, Figures 4 to 10 



Occurrence. — This is the commonest species gf the genus in the 

 District, particular in summer. 



It is to be found along the sides of woodland roads and about 

 rocky places in woods, being most abundant in the vicinity of scrub 

 oak ; but it is also to be met with scattered widely over open fields in 

 which there are small isolated oaks or which are bordered with oak 

 scrub. In summer especially it seems to enjoy coursing over meadows 

 where it feeds on the flowers of the red clover, butterflyweed, and 

 asters. It is not infrequently seen in summer sucking moisture from 

 muddy spots, on which it keeps always more or less aloof from the 

 other butterflies. Very early in spring it is often seen flying about 

 the branches of the trees 20 feet or more above the ground. 



