Webworms in Oklahoma

Wednesday, September 30, 2015

With Halloween quickly approaching, some might think massive populations of giant spiders have taken over parts of the state, spinning webs in tree branches as far as the eye can see

Those webs, however, have nothing to do with spiders. Oklahoma is experiencing a wave of fall webworms, which have simply been more abundant than in years past.

“In some years we barely notice them at all,” said Eric Rebek, associate professor in Oklahoma State University’s Department of Entomology and Plant Pathology. “Some years are bigger than others, this year we just happen to have a bumper crop of these caterpillars.”

The webworms prefer pecan and persimmon trees, but can branch out and feed on other trees as needed. While the webs may be unsightly, there is not much to worry about concerning the health of the trees.

“The webworms will do no damage to the actual pecan, but it can defoliate the tree,” said Jackie Lee, OSU Cooperative Extension entomologist. ”The only reason you should be concerned is if you have a lot of webs in the tree, it could cause severe defoliation.”

Even then, the long-term impact on the tree will be minimal.

“By the time they start doing their damage, the trees have already produced enough sugars and starches through photosynthesis to make it through the winter,” Rebek said. “It’s not going to harm the tree at all, as the leaves are soon to fall off anyway.”

Younger trees are more susceptible. Lee suggests removing any webs and webworms from trees less than five years of age.

“It’s very simple,” she said. “Just take a branch and run your hand along the branch to remove the webworms, or prune out those branches, making sure to dispose of the worms.”

The webs themselves are created by a group of worms for protection as barriers from their own natural enemies, like arthropod predators, parasitoids and birds. Soon the worms will begin to fall from the webs and begin the next stage of their lives, pupating in the soil.

The webs will naturally degrade as natural elements, such as wind and rain, take hold.

A SUNUP video on webworms is available at http://sunup.okstate.edu/category/seg/2015-second-half/091915-webworms/.