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Sunflower moth, banded sunflower moth, and sunflower maggot adult.

Sunflower Pest Recap

During 2026, we will be producing a new weekly update on sunflower insect pest activity. This information will be attained via a sampling network of eight locations that are in central South Dakota.

Green leaf with light colored aphids feeding on it.

Soybean Aphid Populations Have Reached Economic Threshold

Based on recently scouting observations, the economic threshold for soybean aphids has been reached. Once thresholds are reached, fields should be reevaluated in 3 to 4 days to confirm the populations didn’t decrease, and if they persist or increase, they should be treated.

Blue green aphids present on a corn tassel.

Aphid Populations Observed in South Dakota Corn Fields

During the last week, we have observed low level aphid populations in corn fields. Although aphid populations can reach high densities in corn, their presence doesn’t indicate guaranteed yield loss.

Dense swarm of mosquitoes in the evening sky

West Nile Virus Update: July 29, 2026

As of July 30, 2026, the South Dakota Department of Health indicated that West Nile Virus positive mosquito pools have been detected in Brown, Codington, Hughes, Lincoln, and Minnehaha counties in South Dakota.

Green cloverworm caterpillar, Thistle caterpillar, and Oblique banded leaf roller.

Several Species of Caterpillars Are Actively Defoliating Soybean

There are several species of caterpillars that have recently been observed in a single soybean field. The species include the green cloverworm, cabbage looper, alfalfa, thistle, and oblique banded leaf roller caterpillars.