October 16, 2000
A total of 40 species of butterflies were seen on the Fermilab site in the year 2000, bringing the total for the past two years to 44 species. The variety of habitats--marsh, prairie, old field, and woods--with some of the wetlands and woods being old remnants make Fermilab an outstanding place for viewing a good variety of northern Illinois butterflies.
The Purplish Coppers were abundant on site this year, again associated with Polygonum coccineum. Two areas where many Purplish Coppers were flying together were around Bullrush Pond and adjacent to the Main Ring Lake near C4. I saw one Purplish Copper in May, several in July, and many in late August/early September. We clearly have a good-sized population of Purplish Coppers breeding on site. Wild Indigo Duskywings were also abundant this year and generally associated with Crown Vetch, which is abundant on site.
Of the ten new species seen this year, three (Delaware Skipper, Coral Hairstreak, and Northern Pearly Eye) are considered somewhat remnant dependent and are probably breeding on site. The Delaware Skipper and Coral Hairstreaks as well as a second population of Eyed Browns were found on the eastern edge of the site, south of Wilson Street in ELM-20. The following table lists what was new for the year 2000 with some comments about each species.
New for 2000 Comments
A common southern species that disperses north by the end of the summer. I saw only a few individuals late in the summer. Atrytone delaware
A prairie/old field species that is probably breeding on site. These were seen in the center of the Main Ring and on the eastern edge of the site in the fields just south of Wilson Street. Epargyreus clarus
(Silver Spotted Skipper)
A common and widespread skipper; surprising that I did not see it last year. Pyrgus communis
More common to the south. I only saw one, on the eastern side of the site. Harkenclenus titus
This looks like a local colony breeding on site. Cynthia virginiensis
(American Painted Lady)
Common, wanders widely, populations fluctuate. Polygonia comma
Common this year in the woods and woods edge. No doubt breeding on site. Libytheana bachmanii
Southern, wanders to the north, just saw this one individual. Enodia anthedon
(Northern Pearly Eye)
Common this year in the woods and woods edge. No doubt breeding on site. Megisto cymela
Probably breeding on site in the woods and woods edge; I only saw one but expect to find more next year.
Seen in 1999
but not in 2000
Comments Battus philenor
This was an unusual stray which I would not expect to see at Fermilab. Eurema lisa
Wanders up from the south; not surprising to not find it every year. Nathalis iole
Wanders up from the south; not surprising to not find it every year. Satyrium acadica
Probably breeding on site and missed it this year. This is one to look for in 2001. Butterfly Data - Peak Count Data for 2000 - Map of Fermilab