If you grow soybeans in Indiana, you know that stinkbugs are a possible threat every year. Most years they stay below threshold levels or come in late enough in the season that they do minimal damage. However, over the past several seasons they have become numerous enough in fields here and there to cause damage.

Part of the damage they cause is feeding on pods, notes Steve Gauck, a regional agronomy manager for Beck’s based near Greensburg, Ind.

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“When several fields in the southern half of the state were infested a few years ago, they not only damaged beans inside pods, but also opened up those pods to infection by diseases,” Gauck explains. “They can hurt seed quality, which is especially a concern if you’re raising seed beans. And they can be numerous enough to hurt yields, in some cases.”

Beck’s sponsors Soybean Watch ’21.

Spotted in Soybean Watch

When Gauck scouted the Soybean Watch ’21 field for the final time before harvest in late September, he found a few stinkbugs, including some nymphs of green stinkbugs. He even found a couple of pods with damage from stinkbug feeding, but he had to look hard.

“We likely didn’t see them before, and the ones we found later probably arrived late in the season,” Gauck says. “The grower added an insecticide when he sprayed fungicide at the R3 stage of soybean growth. That should have kept them at bay for a while, but it won’t last all the way until harvest. The insecticide is inexpensive, and it’s good insurance if you’re wanting to hold down insect pressure and protect soybean yield and quality.”

The nymphs that Gauck found look like twins to the ones pictured in the Purdue University Corn and Soybean Field Guide for green stinkbugs. In fact, he found one bug the size of the smallest one pictured, and then one the size of the largest nymph. He also found a couple of mature green stinkbugs in the field.

Stinkbugs lay eggs on the underside of soybean leaves. The nymphs that hatch can be a variety of colors, including black, green and orange. There is often a pattern over their back. The nymphs are wingless.

It’s the piercing, straw-like mouth part of the adult that penetrates pods and stings the beans inside, according to the guide.