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RED ALERT: Soybean Gall Midge

Article cover photo
Soybean farmers in Iowa need to scout their fields immediately for presence of the soybean gall midge. On left is a drone image of a field infested with soybean midge. Note that plant death began at the field edges, but soon worked its way into the field. On right is the red larval stage of the midge. (Submitted photo)

By Scott Nelson. Director On-Farm Network

Soybean farmers in Iowa need to scout their fields immediately for presence of the soybean gall midge. A relative of the hessian fly, this insect can devastate soybean fields. In On-Farm Network scouting we have seen fields with 80-bushel yield potential killed in significant portions of the field. The insect was believed to only feed on diseased plants, but our observations indicate the pest will feed on healthy, high yielding soybeans.

This will be a very difficult pest to control, and the first step is to understand where the insect is found in Iowa.

What to look for:

  • Begin by scouting along field edges.
  • Look for dead or dying plants. Symptoms first appear to be drought stress, then the plant completely dies as the larvae plug up vascular tissue and kill the entire plant.
  • The midge will create a gall on the lower stem and sometimes slightly below the soil surface.
  • If you peel back the effected stem tissue, you can see either white or red larvae feeding upon the tissue.

Iowa State University has found the insect in 10 counties in Iowa. Northeast Nebraska and Eastern South Dakota fields are also affected.

Little is understood about this pest, but it could overwinter as one farmer observed a small infestation in 2017 blow up to a large infestation in 2018. From our observations adult flies lay eggs in the stems of soybeans or in the soil. The eggs hatch and larvae burrow into the stem tissue, feed, and cause plant death. Fortunately, we have discovered that the fly is attracted to the same yellow sticky traps used in monitoring corn rootworm beetles. This is hopeful as we could have a tool to monitor adult emergence.

Currently, there are no chemical control options for soybean midge. The On-Farm Network is conducting some on-farm research to understand if pyrethroids can kill the fly stage. We are also establishing collaborations with the major crop protection companies for potential solutions.

"Since experts don’t yet have a good handle on how to control this insect pest, farmers noticing galls and internal larval feeding on their soybeans are encouraged to contact us or Dr. Erin Hodgson at ISU," said Ed Anderson, ISA senior director of research. "The more we learn about this new pest, the faster we will figure out how to manage it in either the adult fly stage or in the larval stage." 

If you identify soybean midge in your fields, please send an email to research@iasoybeans.com or call (515) 334-1055; or contact Hodgson at ewh@iastate.edu.

Areas in the state where presence of soybean midge has been identified (as of Aug. 10).
Bottom: look for galls on the lower stem or just below the soil surface. (Submitted photo)

For media inquiries, permission to republish articles or to request high-res photos, please contact Katie James, ISA Public Relations Manager at kjames@iasoybeans.com. © 2020 Iowa Soybean Association. All rights reserved.

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