Dunes in Illinois

Since I recently blogged about the wonders of the dune community in Indiana, it's only fair that I give some time to the sand dunes of Illinois Beach State Park. The park extends along the Lake Michigan shoreline right up near the Wisconsin border. The dunes are smaller here than in Indiana or Michigan. That's because the prevailing westerly winds blow a lot of the sand out into the lake rather than into or along the shore. The latter process is necessary to sculpt taller dunes.

Bearberry (Arctostaphylus uva-ursi)

Two rare butterflies are found at Illinois beach. They fly very early in the season, so on Friday afternoon, I made my way up to the park to attempt to find them. The Hoary Elfin is an endangered species in Illinois. The caterpillars feed exclusively on bearberry, a rare plant in Illinois. The population of Hoary Elfins at Illinois Beach is the only one known in the state.

Bearberry is a woody plant that grows in prostrate mats

Curiously, Hoary Elfins have never been reported from the Indiana Dunes, despite the existence of ample host plant in apparently similar habitat.

Friday afternoon was very windy, which helped neither the the butterfly watching nor the photography. I only saw about a half dozen elfins. The constant motion of even very low vegetation in the stiff breeze meant that most of my photos were blurry. I did manage to get one decent image.


I was keeping an eye out for tiger beetles during my visit, and only managed to see one. It's a terrible photo, but represents the only time I've ever seen Cicindela scutellaris in Illinois. This one is subspecies lecontii.

Festive Tiger Beetle (Cicindela scutellaris lecontii)

The other butterfly that I was seeking, the Olympia Marblewing, was a no show. I suspect that the wind was just too high. Despite the suboptimal conditions, it's really hard to have a bad day at such a beautiful nature preserve. I even managed to continue my project of trying to get more digital images of butterfly species that I need to include in talks. Just before I reached the parking lot to leave, an American Lady posed very briefly for me. Up until now, my only images of that species have been on film.

American Lady (Vanessa virginiensis)