Crop Injury: Soybean gall midge (Resseliella maxima) is a recently discovered soybean pest found in the Midwestern United States. Since its initial discovery in 2018, it has spread to at least 140 counties. Gall midge larvae feed on the base and lower stem of the soybean plant, hindering the movement of water and nutrients. Symptoms begin with dark, discolored areas that spread from larval feeding sites. Stems become withered, weak, and can eventually break at the base. Plants with high levels of infestation will wilt and die. The adult gall midge does not feed on soybean plants.
Pest Description: Soybean gall midge larvae are tiny and resemble maggots. Young larvae can be clear to white and mature larvae become bright orange. The adult gall midge is small and thin with long, banded legs, mottled wings, and an orange abdomen.
Soybean gall midge larvae revealed within soybean stem. Image: A. Sisson.
Soybean gall midge larva within soybean stem. Image: D. Mueller.
Life Cycle: Soybean gall midge larvae overwinter in the soil, and pupate in early spring before emerging from the soil as adults. Adult midges lay eggs in wounds or natural openings on the lower stems and base of soybean plants. Hatched larvae feed on the stems until maturity, falling off the plant and pupating in the soil. Adult midges live three to five days, and a minimum of two generations of the midge can occur each growing season.
Scouting: Scouting for soybean gall midge should occur after the second trifoliate (V2) growth stage. Infestations often begin as wilting or dead soybean plants at the borders of fields close to areas where soybean was planted the previous year. Look for dark, discolored areas near the base of the stem and peel blackened tissue back to look for small white or orange larvae.
Soybean stem gall caused by soybean gall midge. Image: A. Sisson.
Management: Currently, there are no recommended management practices for soybean gall midge. Studies on the application of seed and foliar insecticides have not proven effective. Further research is underway to determine if other management methods will be effective, including insecticide use and cultural practices.
Check out the Soybean Gall Midge Alert Network for the latest information on this pest.
Developed and reviewed by Justin McMechan, University of Nebraska-Lincoln; Erin Hodgson, Iowa State University; and the Iowa State University Integrated Pest Management Program.