Monday, August 27, 2012

Fall Webworm Prevalent in Central PA

In driving around the region we see a severe infestation of fall webworm showing up......more than in most years.  This pest is easily recognized by the tent-like webs they make at the ends of branches while they skeletonize and consume the leaves.  The webs provide protection from predators.  The caterpillars feed on almost 90 species of deciduous trees, most commonly attacking hickory, walnut, birch, cherry, and crabapple.

Fall webworm is a native pest but entomology experts aren't sure why we are seeing so much of this insect this year.  They suspect it may be due to the very early spring and mild winter we had as this insect has to overwinter in the pupal stage.  Luckily fall or late summer defoliators are much less destructive and stressful on the tree than spring defoliators, like gypsy moth.  The tree has already set a bud for next years growth and as long as the bud is not disturbed the trees will generally refoliate just fine next spring.

The webs can be pruned out or manually removed.  There are also a large number of insecticides labeled for webworm control.  To be most successful treatments need to be made when webs are small in late June through July.

To read the full Penn State Extension Entomology Fact Sheet click here.

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