By Linda Geist
The soybean tentiform leafminer (STL) moth is no bigger than George Washington’s nose on a quarter.
But don’t underestimate it, says Ivair Valmorbida, University of Missouri Extension state field crops and forage entomologist.
Valmorbida confirmed STL’s presence in 2025 in Cooper County in a field next to a wooded area, its preferred infestation area.
Macrosaccus morrisella feeds on two native plants in the soybean family, American hog peanut and slickseed fuzzybean. It now has adapted to feed on soybean, Missouri’s top agricultural crop. First detected feeding on soybeans in the United States in 2021, STL is most prevalent in Minnesota.
The small moth has wings with orange, white and gray-black marks. Females lay eggs on the underside of soybean leaves. Its larvae feed inside the leaves and form mines that do not cross the midribs or main lateral leaf veins. The mines start small but grow longer and cause small white blotches. Mined tissue dies, reducing leaf area.
Because this pest is so new, management options are still being developed, says Valmorbida. Initial research shows that insecticides with translaminar properties can reduce numbers and mined leaf area in field trials. Screening of soybean genotypes identified certain cultivars that were less susceptible to this recently recognized pest.
Source : missouri.edu