As fall approaches and leaves turn vibrant shades of red, orange and yellow, they could become an "all you can eat" buffet for insects.
The fall webworm, a small hairy caterpillar that feeds on 230 species of trees including oak, black walnut, apple, maple and elm have found their way into East Lansing backyards.
The worm can be found all across Michigan and its population even extends into Canada and Mexico.
"They look worse than they actually are," said Gary Heilig, Ingham County MSU Extension horticulture educator. "Most people don't even treat them. It's not unusual to see 10 or 15 nests in a tree."
Webworms have black heads and two rows of dark spots down their bodies. The webs have a silky texture and are located at the edges of branches. The bugs munch on leaves and branches located within the nest but do not pose a major threat to the host tree in northern states, Heilig said. The webworms will increase the size of their nest area to accommodate the size of the population.
"There's more fall webworms this year than in most years. The population goes up a few years and down a few years," said Dave Smitley, MSU professor of entomology and an extension specialist. "We're definitely in an up year, but it will come down naturally."
Experts said temperature also affects the size of the worm's nest and population.
"The colder temperatures don't give the webworms time to get through multiple generations per year," entomology graduate student Alicia Bray said. "In the southern U.S. they're able to have multiple generations in one year.
"They could pretty much destroy a tree with four generations."
Michigan temperatures don't allow for webworms to pose a threat to trees, but the damage they do can be "unsightly," said Professional Turf Management Inc. President Ron Patterson.
Gary Gierke, owner of Mason-based Express Tree Services, said he receives 10 to 15 complaints a week from individuals concerned about the well-being of their trees.
"People want us to come out and cut (webworms) out of their trees, and I discourage them from doing that," Gierke said. "Then you've got a tree with a bunch of holes in the canopy."
There are several ways to prevent and treat the nests from returning.
"They may just prune the branch," Heilig said. "If it's close enough to the ground, I blast the nest with a strong stream of water, especially while they're small."
Patterson said there is no practical way to prevent the worms from making nests in trees.
"The whole crux of the fall webworm isn't a detriment to the tree," Patterson said. "Environmentally and cost efficient, a spray would have to be used across the board for all deciduous trees and that's not efficient.
"They'll feed within the cocoon area."
Patterson said it's more of a cosmetic issue.
"Some people just don't like the look of it."
A bug prevention product from the Tanglefoot Company can also be used in the eradication of webworms.
"Put up Tanglefoot at the base of the tree," Gierke said. "It's like a big bug trap. It's totally non-toxic, no chemicals are involved."
Ingham County MSU Extension Services recommends pruning branches or the use of a bacterial insecticide called Bacillus thruingiensis. It's used when the webworm larvae are small. The burning of nests is not recommended.
"People love to burn the nests only if it's low enough to where they can reach it," Heilig said. "It'll pretty much smoke all the caterpillars.
"That kind of extreme heat can destroy a branch. When I talk to people about fall webworms, about half have burned it up. I wouldn't suggest burning them. It's not a recommended practice by us."
