European corn borer/ corn earworm update

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Pheromone trap catches for European corn borer and corn earworm continue to be very low. In most areas of Michigan, we have not yet reached the 1450 degree-days (base 50) required for the second adult flight of corn borer moths. Because of high temperatures earlier in the season, this flight may start a bit later than 1450 degree-days. We don’t know yet how large the second flight will be.

You can find current degree-day accumulations for your area by consulting the degree-day table in this issue of the Vegetable CAT Alert, or by accessing the MSU Enviro-weather website at Select the nearest weather station from the pull-down list at the top of the page, then click on “vegetables”. The first selection, “Weather Summary” will generate a table that includes degree-day data. Look in the degree-day base 50 column to find DD50 accumulations by date.

Corn earworm trap catches continue to be very low throughout Michigan

Since corn earworm (unlike European corn borers) cannot survive the Michigan winter and must migrate into the state each year, precisely when they arrive each year and how many come is variable. Michigan corn earworm trap catch is now included on Penn State’s PESTWATCH sweet corn monitoring system’s website ( Growers can see the average daily trap catch for corn earworm at six or more Michigan locations and in neighboring states. This site will help us track the northern migration of corn earworm into Michigan each year.

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