Soybean Insects
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Best Management Practices for Soybean Production
This is your unbiased, research-based guide to soybean production to help increase yield, reduce input costs and protect your investment.
Economically Damaging Soybean Aphid Populations Detected
Soybean aphid populations continue to grow in South Dakota. This week, counts near Volga ranged from approximately 280-700 aphids per plant. Observations of these populations indicate that they are healthy and will continue to increase.
Scout Soybean in Drought-Affected Fields for Twospotted Spider Mites
One of the pests that typically shows up during drought conditions is the twospotted spider mite (Tetranychus urticae). Infestations of this pest were recently confirmed in Eastern South Dakota soybean and corn.
Crops
During the growing season, SDSU Extension provides weekly production recommendations.
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.
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.
It’s Time To Scout for Soybean Aphids
While scouting soybeans last week, we observed small populations of soybean aphids. These populations suggest that the infestation was recent. In 2025, we observed similar small infestations that took a long time to increase.
Dectes Stem Borer Adults Detected in South Dakota Soybean
Dectes stem borer adults have been collected from soybean in Southeastern South Dakota this week. As a reminder, the larvae of insect pest are capable of reducing soybean yields from 0-17% due to its feeding activity inside of the main stem.
Soybean
SDSU Extension is your partner to increase yields and improve efficiency.
Large Grasshopper Nymph Populations Detected in Southeast South Dakota
This week we received several reports of large grasshopper populations originating from southeast South Dakota. The populations were well above threshold and actively defoliating crops.
Fungus Gnats Affecting Soybean Emergence
We have recently received a report of a maggot attacking soybean seedlings. During most years, we would immediately expect this to be a case of seedcorn maggots, but it was fungus gnat larvae.