Walnut Caterpillar

Walnut Cats on the Prowl

Walnut caterpillars are producing noticeable defoliation in southwest Ohio. The moth caterpillars feed in groups, or "colonies," of 10-30 individuals throughout their development which is why their defoliation is often focused on a single branch or a group of adjoining branches. However, it's also why multiple colonies can quickly defoliate small trees.
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Joe Boggs
Walnut Caterpillars on the Prowl boggs.47@osu.edu Fri, 07/15/2016 - 16:14

Walnut caterpillars (Datana integerrima) are native insects meaning that year-to-year population densities are usually kept in check by predators, parasitoids, and pathogens (the 3-Ps).  However, we occasionally see "outbreak years" when caterpillar numbers surge ahead of the combined natural suppression provided by the 3-Ps.  I'm not suggesting we are experiencing an outbreak season, but walnut caterpillars are certainly not hard to find!  In fact, I've come across the characteristic patchy defoliation produced by colonies of these caterpillars on their namesake host in two...

Published on
Authors
Joe Boggs