Painted Lady Butterflies Becoming Problematic for Soybean Fields

Some western Iowa fields are getting sprayed to get rid of painted lady butterflies that have become problematic for soybean crops.

Iowa State University Extension field agronomist Joel DeJong said the agricultural community believes this year’s influx of the painted lady butterfly, or thistle caterpillar, is the largest ever in Siouxland.

“We see a few each year, but not to this extent,” DeJong said Friday.

Painted lady butterflies have been known to chew half of the leaf area on soybeans. Farmers last month started hiring flying crews to spray their crops in an insecticide.

“You (spray to) kill the larvae, you don’t do an effective job killing the adults (butterflies),” DeJong said.

The butterfly normally passes through the region but is spending more time there than usual. DeJong said the climate apparently made it possible for the insect to “thrive” this year.

“We are hoping they migrate before huge egg-laying,” he said.

DeJong said airplane businesses get involved in crop-dusting in a short window of days. Some come from outside Iowa, journeying to trouble spots nationally over the course of the growing season.