Butterflies on the rebound after cold and wet spring

Cold and wet weather is tough on butterflies — particularly their caterpillars — in spring and early summer.

But the good news is that when conditions improve, butterflies seem to bounce back.

“It really depressed them early when we had the real cold weather,” said Dave Nance, retired biology teacher at Pana High School who operates the Tallgrass Butterfly House in Anderson Prairie Park.

“In May, it was not that nice — really cool,” he said. “During the second week of May there were frost warnings, and the butterflies were really coming on before that.”

Nance catches native butterflies to stock the butterfly house that is located on Chestnut Street just south of the high school.

“I’m starting to see the rebound — finally,” he said.

Great spangled fritillary on butterfly milkweed.

Doug Taron, curator of biology at the Peggy Notebeart Nature Museum in Chicago, said cool weather delays the development of caterpillars.

“It slows down growth, and they spend more time in the caterpillar stage,” he said. “And that extends the period of vulnerability to predators and disease.”

Like a farmer’s crops standing in the field waiting to be harvested, the longer it takes, the more likely something bad might happen.

Caterpillars are susceptible to bacterial, mold and fungal infections, Taron said.

“This year we had a cold, wet spring in the Chicago area, and we are seeing numbers that are a little bit depressed,” he said.

But Taron says it depends on the timing and whether or not the rainy weather is coupled with cool temperatures.

“The weather is particularly problematic if you have a wet period combined with cool temperatures,” he said.

Three of the past four years have been tough ones in the Chicago regions, but last year was a “fantastic year” for butterflies he said.

“I’m not worried about butterflies taken as a group,” he said.

Angella Moorehouse, a biologist with the Illinois Nature Preserves Commission, coordinates volunteer butterfly counts, including one held in Mason County June 19 and one in the Beardstown area Tuesday.

The Mason County count includes three state nature preserves with roadside stops where wildflowers were blooming.

“We ended up with 40 species, which is about average, and 1,659 individuals,” she said of the Mason County totals.

“That’s very close to the all time record of 1,672 (recorded in 2004).”

Chris Young can be reached at (217) 788-1528 or .(JavaScript must be enabled to view this email address).

Zebra swallowtails are attracted to common milkweed.

TALLGRASS BUTTERFLY HOUSE

The Tallgrass Butterfly House is a showcase for native butterflies that is adjacent to a hiking trail through Anderson Prairie Park in Pana.

Retired Pana High School biology teacher Dave Nance and his wife, Jean, staff the house on a volunteer basis each summer.

Anderson Prairie Park is located along Chestnut Street, just south of Pana High School.

The park is a linear park including an abandoned railroad bed that now serves as a walking trail.

The prairie sections are registered with the Illinois Nature Preserves Commission.

The Tallgrass Butterfly House is open from 11 a.m. to 5 p.m., Monday through Saturday.