150 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



The lisa is fond of flowers, especially of yellow flowers such as 

 those of the goldenrod. Whenever possible it prefers to rest on 

 yellowed or whitened leaves. The males are very fond of sucking 

 moisture from mud, which they do in little compact companies of 

 from 4 to a dozen or more, sometimes as many as 20. There may be 

 several companies on a single muddy spot. Usually these companies 

 include more or fewer of the males of the yellow clover {Colias 

 philodice) , the relative proportions of the two being roughly the same 

 as in the near-by fields. On a muddy spot they will at once collect 

 about a dead yellow butterfly, or even about a bit of yellow paper. 



This butterfly occasionally migrates in immense swarms, but no 

 such phenomenon has been reported from the District. 



Season. — The lisa appears just before the middle of May in small 

 numbers and continues to emerge throughout June. Its numbers 

 increase during summer, and after the first of August it is very 

 common. Still increasing in abundance, it reaches its maximum 

 about the middle of September and continues abundant until the cold 

 weather puts a stop to its activities. Fresh individuals are found 

 continually from its first appearance. 



Notes. — About Washington as elsewhere the lisa varies consider- 

 ably in color. The males range from pale to deep yellow, sometimes 

 tinged with chrome. The females range from light yellow to a 

 slightly yellowish white. The size is also variable. The largest 

 female at hand has the fore wings 21.5 mm. in length, and the largest 

 males are of equal size. On the other hand, dwarfs of both sexes are 

 not uncommon. 



A curious male taken at Cabin John on September 11, 1928, has the 

 apex of the fore wings broadly rounded off so that the costal border 

 is scarcely longer than the lower border; the outer border is convex 

 and the wings are broadest just below the middle of the outer border. 



Remarks. — The only pupa of this butterfly which I have seen in its 

 natural position was found by Hugh Clark on the stem of a pigweed 

 {Chenopodium alhum) about an inch above the ground. 



In a series of 20 males taken on October 6 and 7, 1928, the length 

 of the fore wing was 14-20 mm., averaging 19 mm. ; 4 females had 

 the fore wing 17-20 mm., averaging 19 mm., in length. 



Genus COLIAS Fabricius 



COLIAS EURYTHEME (Boisduval) 



Obange Clover 



Plate 26, Figures 1 to 8 



Colias eurytheme Luggek, Proc. Ent. Sec. Washington, vol. 1, no. 2, p. 61, 18SS. 

 Occuri^ence. — Abundant throughout the District and the surround- 

 ing country, being found in all open fields and meadows. It is 



