Illinois hunting and fishing

A regal fritillary nectars on common milkweed at the Sand Prairie Scrub Oak Nature Preserve near Kilbourne. Photos by Chris Young.

Butterfly numbers down, Japanese beetles up during annual butterfly survey

June 27, 2012 at 07:00 PM

The early spring seemed to knock a lot of things out of sync this year, and the results of the annual Mason County Butterfly Count were no different.

Only 29 species were tallied during this year’s count held June 16, down from a high of 49 in 2004.

This time, 347 individual butterflies were counties, down from 1,660 last year.

The count is a one-day snapshot conducted in three nature preserves, and it appeared that many of the usual species had come and gone earlier in the season.

The count normally is held in mid-June.

Many of the usual prairie wildflowers had finished blooming, including important nectar plants like pale purple coneflower.

Regal fritillaries, listed as Illinois state-threatened, were few.

Only eight were counted this time.

In some years, hundreds of the bright orange and black butterflies are seen in a pair of sand prairie habitats near Kilbourne and Havana.

The high count of 723 was tallied in 2004.

One alarming development was the presence of Japanese beetles in the nature preserves.

Normally considered a pest of areas with lots of turf grass, they weren’t expected to be a big problem in areas where grass is not mowed.

However, many milkweed flowers were so covered in Japanese beetles they were weighed down and drooping.

Illinois hunting and fishing

Even leadplant, a signature plant of high-quality prairies and savannas, was attacked.

Both are important plants for butterflies and other pollinators.