A number of caterpillars can cause damage by defoliating the leaves or feeding on the seed pods of soybeans in Mid-South fields. Farmers need to be able to differentiate between them so they know which pest they’re dealing with.
“Many different species of caterpillars crawl along in that looping, inch-worm fashion,” says Sandy Steckel, Extension assistant with the University of Tennessee. “So you really can’t identify what the larva are just because they move this way.
“Both green cloverworms and soybean loopers, two pests of soybeans, may move in this inch-worm fashion,” said Steckel, who discussed some of those characteristics in a video from the online Milan No-Till Field Day held earlier this summer. “But these pests have very different treatment thresholds. That’s why it’s important to correctly identify them.”
Green cloverworm, for example, is the most common defoliating caterpillar in Tennessee soybean fields. It may be found at any time during the growing season. It is green, slender and grows to about 1 inch in length.
“All caterpillars we’re interested in have legs at the front of the body called true legs and this pair at the end of the body near the abdominal segment,” she said. “The legs we’re interested in are these legs in the middle. They are called pro legs, and the number of legs in the middle of the body is often how we can distinguish between caterpillar species.
“The way I remember to tell if it’s a green cloverworm vs. a looper is that cloverworm has three syllables, and cloverworms have three pairs of legs in the middle of the body. Looper, on the other hand is two syllables and two Os and two pairs of pro legs in the middle of the body.”
For more information on identifying pests in soybeans, visit https://milannotill.tennessee.edu/research-tours/ and look for Tour C – No-Till Soybeans.