BUTTERFLIES OF THE DISTRICT OF COLUMBIA 81 



These remarks were based on observations made early in the 

 autumn of 1925 in the fields along the Conduit Road 2 miles beyond 

 Cabin John. Here the large dark form was very abundant, and 

 30 or 40 or more could easily be started from the grass and captured 

 in the course of a couple of hours. The caterpillars were very 

 common, and a number were raised, all coming out the dark form. 

 The small light form was very scarce. 



Since that year I met with no typical examples of the dark form 

 until late in the summer of 1929, when it again appeared, though in 

 small numbers. 



The earliest date for the large dark form is September 9. 



I have been unable to find the dark form elsewhere in the vicinity 

 of the District. But intermediate specimens showing an approach 

 to it in all ways are frequent late in summer in the low, damp hol- 

 low at Silver Spring, parallel to and near Blair Road, just opposite 

 the entrance to the Hyslop estate, while in the higher and drier 

 regions in the same fields the small light form is common. 



Carl Heinrich examined the male genitalia of typical examples 

 of these two forms and found no differences. 



Hahits. — This butterfly has been given by some authors (for in- 

 stance, Maynard and Scudder) as frequenting dry, hot places, and 

 by others as found in fields near swamps (John Abbot), or pre- 

 ferring meadows and lowlands (F. H. Sprague). From my experi- 

 ence with it I am inclined to believe that it occurs equally in both 

 types of localities, but tends in the moist areas to develop a special 

 local and relatively inactive form. In Massachusetts, where only 

 the small light form occurs, I have taken it on the hot sand dunes 

 at Ipswich and also in a boggy hollow in some extensive hilly 

 pastures at Essex. 



The buckeye has a rapid, direct flight, alternately flapping with 

 a few quick and nervous wing beats and then sailing for some dis- 

 tance with the wings held horizontal^. Its usual rate of progress 

 is 12 miles an hour, but when much frightened or in pursuit of 

 some other insect it will fly at the rate of 15 or 16 miles an hour 

 for 50 feet or more. After going a greater or lesser distance in a 

 straight line it often turns abruptly to the right or left so that it is 

 difficult to follow with the eye. It always flies low, from 4 or 5 

 inches to a foot above the grass tops, and between 1 and 2 feet above 

 open and bare ground. In flight the light form sometimes appears 

 more like a grasshopper than like a butterfly. 



It is very fond of flowers, especially those that rise some distance 

 above the grass, and shows a marked preference for white flowers, 

 such as those of the wild carrot or the boneset. It is also especially 

 fond of the blue flowers of Ewpatoriutn coelestinutii. When it is 

 feeding, the wings are usually partially expanded, though they may 



