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How widespread is dectes stem borer in Illinois? Help us find out

Nick Seiter

Department of Crop Sciences
University of Illinois

September 1, 2021
Recommended citation format: Seiter, N.. "How widespread is dectes stem borer in Illinois? Help us find out." Department of Crop Sciences, University of Illinois, September 1, 2021. Permalink
Image of a dectes stem borer larva in the base of a mature soybean stem
Dectes stem borer larvae overwinter in the base of mature soybean stems.

Have you had issues with dectes stem borer in soybean over the last several years? We are kicking off a project this fall to better understand dectes stem borer populations in Illinois – where they are most common, how severe they are, and how they vary from year to year. If you are interested in contributing to this effort, we are seeking volunteers willing to do the following:

Choose one or more soybean fields. This could be a field where you have had dectes problems in the past, or not; we will ask for information on tillage, variety, location, and history of dectes stem borer infestation.

Scout the field for dectes stem borer tunneling. Between R6-R8, split the main stem of 25 plants in the field and look for dectes stem borer larvae and their tunnels.

Send us your counts. We will provide a data sheet and protocol for you to follow; fill it in and email it to me at

How does this help soybean farmers? This will provide us with reliable information on dectes stem borer distribution in Illinois and help us to identify areas where farmers should be more vigilant for this pest. If you send us counts, we will provide you with a report of our findings at the end of the season.

If you would like to participate, please send me an email at (preferably with the subject “dectes stem borer monitoring”), and I will provide you with a more detailed protocol and datasheet. Happy scouting!


Contact: Nick Seiter, Field Crop Entomologist | | (812) 593-4317

Note: We made a fact sheet a couple of years ago on dectes stem borer, which you can access at


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