October, 2026
by Sean Tracy, Class of 2015
This past April, I was invited by Yvonne Homeyer, president of the local chapter of the North American Butterfly Association, to conduct butterfly surveys at Washington University’s Tyson Research Center. No butterfly surveys had been conducted since the early 2000s by Yvonne Homeyer and the late Jim Ziebol.
After meeting with the leadership of Tyson and one of their researchers, we were tasked with six locations to survey, if possible, once a week. Due to the ruggedness of Tyson, a four-wheel drive vehicle was required to access some of the locations. Since I do not own a four-wheel drive vehicle, I surveyed other accessible locations when Yvonne was unable to meet.
Over the course of 22 visits from April 6th through October 7th, we observed 50 species of butterflies in a variety of habitats, but primarily woods with some large openings interspersed resembling savanna habitats.
Five genera were encountered: five swallowtail species, seven white and sulphur species, five gossamer wing species, seventeen brushfoot species, and sixteen skipper species.
The rarest butterfly sighted (otherwise known as a casual species) was a Clouded Skipper which was seen from July 27 th -October 7th on six different dates at five separate locations, normally open habitats, scattered throughout the 2,000 acre center.
Clouded Skipper ventral 7/27 Clouded Skipper ventral 10/7
On June 30th, the highlight of all the butterflies we observed over the course of the six month survey was, what we believe, a melanistic Pearl Crescent. Yvonne spotted the aberrant butterfly at a location we had surveyed throughout the season. The butterfly was only seen once. I have forwarded the aberrant butterfly photos to other experts in the field of lepidoptera, but without a DNA sample, the exact species cannot be determined.
Melanistic Pearl Crescent (dorsal) Melanistic Pearl Crescent (ventral)
As another year of butterfly flights come to a close, I’m looking forward to surveying Washington University’s Tyson Research Center’s property starting on a warm spring day in March 2027.