Washington Area Butterfly Club
Field Reports
October 1999
- Harry Pavulaan
- Leesburg, Loudoun Co., VA. Having received reports of unusual Pierid activity in the vicinity of Leesburg Airport, I contacted the airport administrator for permission to survey butterflies on the airport grounds.
Permission was granted to survey the mowed fields around the north end of the runway. Habitat consisted mainly of weedfields that were mowed very close to the ground, providing a minimum of cover, yet allowing Asters
to bloom profusely at only a few inches of height. Fringe areas along the highway were unmowed, allowing Asters to achieve full height of about 4'. An uncut weedfield, bordering airport property, consisting mainly of blooming Asters and spent Goldenrods was not surveyed. What surprised me was the abundance of butterfly activity in the mowed habitat.
Summary follows. All counts are based on observations assisted by net-identification. Numbers followed by "+" indicate conservative estimates in the area covered.
- Black Swallowtail (1, in area of mowed Queen Anne's Lace)
- Cabbage White (100+)
- Checkered White (100+, only 4 females, net/release of some to confirm identification)
- Orange Sulphur (100+)
- Clouded Sulphur (25+)
- Gray Hairstreak (1)
- Eastern Tailed-Blue (10+, in areas with abundant Crown Vetch)
- Variegated Fritillary (3 females displaying egg-laying behavior)
- Buckeye (25+, mainly in unmowed fringe)
- Mourning Cloak (1, resting on mowed asters!)
- Pearl Crescent (50+, mainly in unmowed fringe)
- Monarch (10+, only in unmowed fringe)
- Wild Indigo Duskywing (2, found only in an area with abundant Crown Vetch, net/released)
- Sachem (7)
The big surprise was the sheer number of Checkered Whites present at the location. This is the largest colony that I have ever observed! I attribute this to the Airport's practice of maintaining close-cut weed fields, while at the same time not introducing grass monoculture, as is the prevalent practice in this region. Checkered whites appeared to be right at home here, and I am now convinced that this is their primary habitat in the east. A similar habitat near Moorefield, W.V. and a cow pasture in Romney, W.V. contained similar close-cut or grazed habitat that contained large numbers of Checkered Whites this year. On the return trip back home, I stopped at several fields in Ashburn and Sterling which contained blooming Asters, but found no Checkered Whites at any of these locations.
One important note is that Checkered White behavior seemed somewhat more "agitated" than observed in spring. They still maintained a more straight flight direction and consistent wingbeat than the Cabbage Whites which shared the habitat, but wingbeat was extremely rapid, changes in direction were frequent, and the relatively pointed forewing of the males was generally plainly visible in flight. Female Checkered Whites are conspicuously grayish in flight, due to heavy dark wing patterns.
Now to get permission to survey Dulles Airport!
- To Field Reports Home Page
- To Washington Area Butterfly Club Home Page