Soybean Tentiform Leafminer Emerges as New Crop Threat

Tiny Leafminer Moth Poses Big Risk to Soybean Yields

The soybean tentiform leafminer (STL) moth is small, but it can cause notable damage to soybean crops. Ivair Valmorbida, University of Missouri Extension state field crops and forage entomologist, cautions producers to take the pest seriously.

Soybean tentiform leafminer was confirmed in Missouri during 2025, with detections in Cooper County, Missouri, especially in soybean fields bordering wooded areas, which provide favorable habitat.

Known scientifically as Macrosaccus morrisella, soybean tentiform leafminer originally fed on native legumes such as American hog peanut and slickseed fuzzybean. In recent years, the insect has shifted to soybeans, Missouri’s top crop. The pest was first documented on U.S. soybean fields in 2021 and has been most prevalent in Minnesota, though its range continues to expand.

Adult moths are marked with orange, white, and gray-black patterns on their wings. Females deposit eggs on the underside of soybean leaves. Once hatched, larvae tunnel within the leaf tissue, forming mines that stay between leaf veins. As the mines enlarge, white blotches appear, killing tissue and reducing photosynthesis.

Because soybean tentiform leafminer is an emerging pest, management strategies are still being evaluated. Initial research suggests insecticides with translaminar activity can reduce larval populations and damage. Some soybean varieties have also shown lower susceptibility.

Valmorbida encourages farmers to scout field edges near wooded areas and report suspected infestations to local MU Extension agronomists or by emailing ivairvalmorbida@missouri.edu. Early identification remains critical for minimizing yield loss.

Photo Credit: istock-sandramatic