BUTTERFLIES OF THE DISTRICT OF COLUMBIA 181 



cally all the summer individuals are large, and in August and early 

 in September extremely large examples are not infrequent. 



Local varietal forms. — This butterfly is usually described as dimor- 

 phic, with a single yellow form in the male and tAvo types of females, 

 one yellow and the other brownish black. 



In the vicinity of Washington its peculiarities are properly under- 

 stood only by recognizing the existence of six more or less intergrad- 

 ing forms in the female and three in the male. 



The yellow female with essentially the male type of coloration cor- 

 responding to the yellow male of the small northern subspecies 

 {canadensis) does not here occur so far as known. 



The commonest female form is the well-known brownish-black 

 glaucus (pi. 40, fig. 1). Usually approximately half of all the 

 females are of this type, but the proportion of black to yellow females 

 varies from season to season and from year to year. In the spring 

 brood yellow females as a rule outnumber the black, and, indeed, 

 black females may be relatively rare. In the summer broods the 

 black females usually outnumber the yellow, but in 1927 the yellow 

 females were somewhat more numerous than the black. 



In the black females {glauows) the ground color varies from a 

 rather light brownish to a deep, sooty black. The variation is espe- 

 cially marked on the undersurface of the wings, where the black 

 markings corresponding to those of the males may be scarcely dis- 

 cernible, or may be sharply contrasted against a rather light-grayish 

 or rusty-brown background. An examination of the underside of 

 the fore wings, of which the ground color is alwa3's darker than that 

 of the hind wings, shows that the black band crossing the outer 

 portion of the cell has moved distally so that it is very near the 

 short band crossing the end of the cell. The narroAV area between 

 these bands may be of the same color as the general ground color of 

 the Aving, or it may be on both surfaces a conspicuous, deep yellow 

 to whitish band. Most commonly this band is vestigial, and often 

 no trace of it can be detected. The amount of blue scaling on the 

 upper surface of the hind wings varies somewhat. In the great 

 majority of individuals very abundant blue scales occur basalward 

 about as far as the origin of Ma, enter the cell as far as the position 

 of the narrow black stripe in the yellow forms, and extend forward 

 as far as SCi. Farther within the cell there are often widely scat- 

 tered blue scales, and there are usuallj^ scattered blue scales above 

 SCi. These last are commonly segregated on the inner side, or on 

 both sides, of the position of the black stripe, and are not infre- 

 quently continued onto the lower margin of the fore wing just above. 

 Over the position of the short black band at the end of the cell and 

 of the black stripe blue scales are either absent, or less numerous than 

 elsewhere. On the fore wings near the outer border there is a large 



