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Is Something Still Eating My Wheat?

Posted by Blythe Howell | October 12, 2022

The days of worrying about insects such as Aphids, Hessian fly, or Wireworms damaging the wheat crop will likely be an afterthought until next spring now that the wheat harvest is mostly if not all complete across Eastern Washington. Unfortunately, an often-overlooked insect problem that may be affecting your bottom line is storage pests. The Almond moth, Angoumois grain moth, Flour beetle, Granary weevil, Indian meal moth, Maize weevil, Rice weevil and Saw-toothed grain beetle are various types of insect storage pests and can become problematic if not controlled. Hand samples or grain probes should be used once a month to detect possible insect infestations especially if the grain is to be stored longer the nine months (as a rule of thumb, grain stored longer than 9 months can become susceptible). Visibly damaged grain can also be a possible indicator of pest activity. Grain that is clean, dry (containing less than 12 percent moisture) and free from weeds, weed seeds and dirt can lessen the development of favorable conditions for insect development.

One of the best preventive methods for stored-insect pests is to start with a clean storage facility. Old grain residue has the potential to harbor various insect pests. Therefore, thorough cleaning of the floors, walls, ceilings, cracks, and crevices of the storage facility with an industrial vacuum is recommended.

Remember that old grain can be found virtually everywhere, on combines, augers, trucks, and trailers.

Figure 1. Granary weevil infestation. Source: Ahmad, R., Hassan, S., Ahmad, S., Nighat, S., Devi, Y.K., Javeed, K., Usmani, S., Ansari, M.J., Erturk, S., Alkan, M. and Hussain, B., 2021. Stored Grain Pests and Current Advances for their Management. Postharvest Technology-Recent Advances, New Perspectives and Applications.

Several insecticides can be applied to treat interior walls and floors of storage facilities. These should be applied seven days before filling with grain. If preventative methods and/or treatment of storage facilities are unsuccessful and a pest outbreak is discovered, there are registered insecticides and fumigants that can be used to treat the grain.  Some buyers may not be inclined to accept insecticide-treated grain. Therefore, it is recommended to check with your local elevator before treating. For additional information on other insect pests of wheat, visit the WSU Wheat and Small Grains Insect Resources page.

For questions or comments, contact Dale Whaley by email at or by phone at 509-745-8531.

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