The boys are back in town

May 6, 2020 1:27 PM
Blog Post

Thin Lizzy predicted it in 1976. Actually, the boys and girls are back in town. Over the weekend, the first painted lady butterflies were spotted in Iowa. Why care about this beautiful butterfly? It seems like a distant memory, but remember the thistle caterpillar bonanza on soybean last summer? They are one in the same species.

Painted lady butterfly. Photo by Whitney Cranshaw,

It is not unusual to see these butterflies in Iowa starting in May. They migrate here every summer from the southern US and Mexico. Read more about the life cycle and management in soybean here. Many farmers throughout Iowa have planted soybean or will plant soon. Females will lay eggs on early-vegetative plants. It is way too early to predict thistle caterpillar densities in Iowa soybean this summer, but it is important to scout vegetative soybean.

Thistle caterpillar.
Thistle caterpillar with frass pellets. Photo by Erin Hodgson.


Erin Hodgson Professor

Dr. Erin Hodgson started working in the Department of Entomology, now the Department of Plant Pathology, Entomology, and Microbiology, at Iowa State University in 2009. She is a professor with extension and research responsibilities in corn and soybeans. She has a general background in integrated...