Webworms are giving some Iowans the willies. These webworms have nothing to do with the Internet — they’re real live worms that build silk webs on trees.
Iowa State University entomologist Donald Lewis says the fall webworm variety is quite abundant this year in Iowa. Lewis says the worms start out as little eggs laid by moths, and by this time of year are about an inch-long, hairy, yellow caterpillars.
Lewis says the caterpillars feed on the leaves and spin the silk web as a protection and they stay together in a cluster. Lewis says as they eat the leaves, they have to expand to get to more leaves and the web that started as the size of a softball can expand to the size of a bushel basket. Lewis says the worms are really more of an eyesore than a danger to the trees — as they don’t eat enough leaves to cause a problem.
Lewis says the best thing to do is to remove the ones you can reach — and leave the rest alone. He says don’t try getting up into the tree and try to burn out the webs. Lewis says spraying isn’t really and option either. He says it takes a high pressure spray to penetrate the silk web and that’s difficult to do safely and effectively. Lewis says the worms will soon drop out of the web and onto the ground for the winter anyway.