Farm Progress is part of the Informa Markets Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them. Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Serving: United States
soybean gall midge larvae Bruce Potter, University of Minnesota
Gall midge larvae and damage under soybean stem epidermis, Rock County, MN, 2018.

What to know about soybean gall midge

Recently discovered in the Midwest, the pest can directly infest soybean plants.

By Bruce Potter, IPM specialist and Bob Koch, Extension entomologist

Recently described as a new species, the soybean gall midge, Resseliella maxima (Gagné), is the first member of the genus Resseliella reported from soybean. It is a member of the rather large and diverse family of flies, the gall midges (Diptera: Cecidomyiidae). 

The larvae of many gall midges feed on galls formed in plant tissues. However, some species do not form galls. Some feed on fungi and decaying organic matter, and the beneficial aphid midge is a predator of aphids. Other crop pest species include the wheat pests, Hessian fly and wheat blossom midge, and a species that is a pest of Asian soybeans. 

Discovery of gall midge in the Midwest

In June 2018, soybean growers in western Nebraska, eastern Iowa and eastern South Dakota began to notice soybeans wilting and dying, particularly along field edges. The stems were brittle near the base with dark lesions. Beneath the epidermis of the lower stem of affected plants, they found small, orange, gall midge larvae. Later in the season, soybean stems were breaking where the midge injury occurred. Crop losses were significant in many fields.

In August 2018, we received samples from a Rock County, MN soybean field where small, pale to bright orange gall midge larvae infested lower portions of soybean stems below the epidermis (Figure 1). In this field, and another in Rock County, injury symptoms were similar to those reported in neighboring states.

In previous years, these midge infestations were presumed secondary to previous soybean injury from hail and disease. However, during 2018, the relationship of gall midge infestations to previous stem injury became less clear, and it is now believed that these insects are able to infest soybean plants directly.

Two species suspected

There appeared to be two types of soybean gall midge reported in MN during 2018. Additional reports from southeast, central and west central Minnesota found gall midge larvae most often associated with Sclerotinia white mold. The larvae were found on all parts of the stem, not just under the epidermis of the lower stem. They were found in white mold mycelia on the stem surface, inside the stem pith and also, more rarely, inside pods.

Justin McMechan, UNLsoybean gall midge distribution

Soybean gall midge distribution.

Based on differences in how soybean was being injured, it was suspected that more than one species of midge may be involved. Larvae from a Rock County and a McLeod County infestation were submitted for comparison with those collected in other states.

Recently, Dr. Ray Gagne determined both of these types of infestations were from the same species, Resseliella maxima. This means that this insect, and its potential for damage, may be widespread in Minnesota (Figure 4).

Little is known about the insect’s biology and less is known about management. Will this gall midge persist in areas where it caused economic concern in previous years? Will the soybean gall midge eventually cause economic problems over a wider geography, including MN soybean fields? What management tactics will be effective? With the help of soybean checkoff funding, researchers in several states are working to find the answers needed to understand economic risk and develop management strategies. 

Look for larvae damage

It is unlikely that you will encounter any of the tiny, 1/4-inch-long mosquito-like soybean gall midge adults with distinct banding on the legs (Figure 5). During 2019, look for damage from the larvae. Look for wilting soybean plants, particularly on field edges adjacent to 2018 soybeans. Peel back the soybean stem epidermis and split stems to look for the small white to orange larvae.

Contact us

We are looking for fields to collect soybean gall midge adults and larva as well as isolate any associated soybean pathogens.

If you notice soybeans with symptoms and larvae resembling the gall midge please let Bruce Potter ( or Bob Koch ( know.

Source: University of Minnesota

The source is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.

TAGS: Insects
Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.