Squash bug activity is increasing in Michigan cucurbit fields

Scouting for squash bug eggs is necessary if you grow cucurbits.

To detect squash bugs in the field, Michigan State University Extension advises that regular scouting of leaves is necessary. The damage symptoms include wilting of leaves initially and ultimately damaged leaves will appear black or dried out. Later in the season, these insects will also feed on fruits. Threshold is reached when the average number of egg masses (meaning groups of eggs) is greater then one egg mass per plant.

Check 5 leaves in 10 different locations spread throughout the field to determine if you have reached threshold. Seedlings, new transplants, and flowering plants are the most critical growth stages to monitor, as these are the stages when the most damage can occur. If the threshold is exceeded, an insecticide application is warranted. Check  MSUE bulletin E-312 for more information on insecticides registered in your crop.

Squash bug eggs Squash bug eggs and nymphs
Left, Squash bug eggs on a watermelon leaf. Right, Squash bug eggs hatching into nymphs.

To see more photos of the squash bug adults, nymphs and eggs, and to read more about its biology, check out this squash bug factsheet from the University of Minnesota.

Dr. Szendrei’s work is funded in part by MSU‘s AgBioResearch.

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