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Adam Varenhorst

Assistant Professor & SDSU Extension Field Crop Entomologist


Berg Agricultural Hall 220
Agronomy, Horticulture & Plant Science-2207A
University Station
Brookings, SD 57007

As the SDSU Extension Field Crop Entomologist I serve South Dakota stakeholders by addressing insect pest issues in field crops. I conduct applied research that focuses on corn, soybean, wheat and sunflower. I also assist the other extension entomologists to address questions pertaining to insect questions for the home and garden, urban insect pests and general entomology questions.

Also by Adam Varenhorst

Green caterpillar with white stripe present on the side of the body. Caterpillar has three pairs of abdominal prolegs.

Green Cloverworms Causing Defoliation in Soybean

Populations of green cloverworm, a caterpillar pest of soybean, have been increasing over the last couple of weeks in South Dakota. Although green cloverworm caterpillars feed on soybean leaves, defoliation rarely results in economic loss. However, reports of increasing populations of green cloverworm and increasing amounts of defoliation suggests that scouting for this insect pest is warranted.

Close-up of several black caterpillars feeding on a green sunflower leaf.

Checkerspot Caterpillars in Sunflower

While scouting sunflower near Sturgis this week, we came across outbreak levels of checkerspot caterpillars that were defoliating the plants. Similar sightings have been reported throughout Western and Central South Dakota in recent weeks.

Two flies side-by-side. The left fly is a Western horse fly. The right fly is a deer fly.

Horse Flies and Deer Flies Becoming Abundant

The above-average precipitation this year has led to increased numbers of horse flies and deer flies across South Dakota. Widespread flooding and an overall abundance of available water has made conditions perfect for these flies.