Caterpillars in Soybeans

Soybeans are blooming now in a large number of Pee Dee fields.  Foliage feeding caterpillars can found pretty easily now when scouting.  Soybeans can tolerate a fair amount of foliage feeding before bloom (30% defoliation), but during and after bloom that tolerance drops considerably (15%).  Regular scouting should be going on now to monitor defoliation.  Below are a few of the different caterpillars that are active right now.

Green Cloverworm

Green Cloverworm

Soybean Looper

Soybean Looper

Yellow Striped Armyworm

Yellow Striped Armyworm

Corn Earworm

Corn Earworm

Color and size can vary making identification confusing, so refer to the graphic below for some distinguishing features to look out for.

Field ID Lep

It’s important to know what you have in your field before making spray decisions as some caterpillars are more destructive than others; therefore, thresholds for each differ.  Here are a couple tables from the SC Pest Management Handbook outlining the thresholds when scouting with beat cloths or sweep nets.

Beat ThresholdsSweep thresholds

Be sure to check at least 2 separate areas of the field and sample each area twice.  If you can not make a clear decision whether or not to make a treatment after that, check an additional area or two.  If fields are found to be over threshold, labeled insecticides and there rates can be found in the Soybean Insect Control section of the SC Pest Management Handbook.  Additional scouting information and thresholds can be found there as well.

For weekly updates on insect in cotton and soybeans, check out Clemson Entomologist Jeremy Greene’s Cotton and Soybean Insect Newsletter.

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