Soybean gall midge larvae found in Dakota County, MN

by Robert L. Koch and Arthur V. Ribeiro

Soybean gall midge larvae were found infesting soybean plants in a field near Rosemount in southeast MN on July 15, 2025. This is the first detection of this insect in Dakota County, which continues the eastward expansion of the known range of this pest. The infested plants were mainly located on an edge of the field adjacent to a corn field. The level of infestation on the edge of the soybean field was relatively low, with only 3.2% of soybean plants infested with soybean gall midge larvae. The infested plants showed the typical darkened lesions at the base of the stems near the soil surface, but none of the plants were wilting or dying. We will continue to monitor this field and others in the area.

 

As summer progresses (through August), it typically gets easier to detect soybean gall midge infestations because more plants become infested and infested plants become more symptomatic (wilting, dying and lodging, in addition to the darkened lesions). Bruce Potter (Univ. of Minnesota, retired) and Justin McMechan (Univ. of Nebraska - Lincoln) have useful videos explaining how to scout for soybean gall midge.

If you detect soybean gall midge in your fields, please contact me (koch0125@umn.edu). We are interested in documenting how widespread the infestations are of this pest in Minnesota, and we are in need of additional sites to perform research to develop management strategies for this pest.

Note: If white mold develops in your fields, please be aware that there is a similar-looking insect called the white-mold gall midge that feeds on the white mold fungus and can be easily confused for soybean gall midge. White-mold gall midge is not a crop pest.