BUTTEEFLIES OF THE DISTRICT OF COLUMBIA 167 



High School in Washington (A. B. J. Clark), and another was cap- 

 tured in the National Zoological Park (H. U. Clark). 



There are no records from this time until 1930, when Hugh 

 Upham Clark captured a female in Rock Creek Park on September 

 16, and I took a male in the meadows beyond Cabin John on Octo- 

 ber 15. 



On April 29, 1931, when with Dr. and Mrs. Torsten Gislen and 

 Miss Doris M. Cochran, I saw two individuals along the border of 

 an open field near the lowest of the Paint Branch bogs. Returning 

 to the same place with Hugh Upham Clark on May 3, I saw five 

 more, of which two, both females, were caught. A male was cap- 

 tured here on May 9. In this field the wintercress {Barbarea vul- 

 garis) grows in great abundance near the woods and also to some 

 distance within the borders of the woods, and it was in the area 

 where the wintercress grew thickest that the butterflies were seen. 



Returning to the same field with Hugh Upham Clark on May 30 

 and 31, I found the late-spring form of this butterfly very common, 

 while a few of the early-spring form were still on the wing. It 

 was far more common than the very infrequent cabbage butterfly 

 {Pieris rapae)^ of which only two or three were seen on May 30 and 

 none on May 31. Instead of being confined more or less closely to 

 the borders of the woods the butterflies were scattered everywhere 

 over the open fields, being especially numerous in the higher and more 

 barren portions. One or two, or even more, were always in sight. 

 On each day 11 were caught in about an hour and a half, and many 

 more were seen. A mated pair and two fluttering about each other 

 were caught in immediate succession, so that I had four in my net at 

 one time. 



These are the only records for the early-spring form {vernalis) 

 and the late-spring form for this region. 



Where the butterflies came from I do not know. I did not find the 

 species in the same field during the preceding summer. 



Habits. — The early-spring form {vernalis) of the checkered white 

 frequents the borders of woods rather than the more open portions 

 of the fields. But it never enters the woods, if badly frightened 

 always making directly off over the open country. It is to be looked 

 for especially where such plants as Barbarea vulgaris and /Sisym- 

 bHvmi thalianum grow in abundance. 



It has a fast, direct, and fluttering flight with rapid wing beats, 

 and usually keeps between 3 and 4 feet above the ground or a foot 

 or two above the tops of the plants over which it flies. When alarmed 

 it makes off in a straight line with extraordinary speed. The flight 

 of the early-spring form of Pieris protodice is very much like the 

 flight of Anthocharis genutia, and, indeed, it is very easy to mistake 

 66544—32 12 



