Perhaps you’ve noticed the increase in web-like ‘tents? at the end of tree branches throughout the area in the past few weeks.
Though the ‘tents? do not look too appealing, they are not as bad for the trees as tents created by other seasonal insects.
‘When people see something as obvious as these webs growing on their landscaping, they get concerned,? said Brad Jacobsen of Jacobsen’s Flowers & Garden Town in Lake Orion.
Jacobsen has received a couple of dozen calls in the past few weeks, including some cases where the webworm is being confused with tent caterpillars, dangerous insects that appear on trees in the spring.
‘Although it’s annoying, your plants are going into a decline state anyway, and the extension service (through Michigan State University) doesn’t recommend spraying,? Jacobsen noted.
Reenae Tulip, director of Orion Township’s Buildings and Grounds Department, agreed with Jacobsen’s assessment.
‘What I usually tell people with fall webworm, is it’s not as big of a concern, because it does happen so late in the season,? she said.
‘With the eastern tent caterpillar, the nest is down in the center of the tree, whereas the fall webworm sits on the ends of branches,? Jacobsen added. ‘That’s the easiest way to tell them apart.?
Though the webworm tents are bigger than the eastern tent caterpillar’s tents, there are not nearly as many worms living in each tent.
The tent caterpillars prefer flowering or fruit trees, and will destroy the foliage on such trees, often destroying the tree in the process.
Jacobsen said the webworm will get on any type of deciduous tree, but rarely produce such harmful circumstances.
Ash, crabapple, hickory and walnut trees are among the fall webworm’s favorite targets.
In a recent Landscape Alert Newsletter, part of MSU’s extension program on Integrated Pest Management Resources, Entomologist Dave Smitley said the half inch-long, yellowish-gray webworm caterpillars stay in their tents during the day, and feed on tree leaves at night.
‘In most cases, each tree has three or four tents,? wrote Smitley. ‘They look bad, but cause little harm to the trees.?
‘Tree health is not affected until more than 50 percent of the foliage is consumed, and even then, the trees usually come back just fine the following spring.?
Smitley said pruning-out infested branches is a good strategy, if the branches are in reach.
Jacobsen said most insecticides will eliminate the web worm if tree owners choose to take that action. He recommended using Sevin, because it’s the best option for the environment.
Smitley added that spraying the foliage around the tents will prevent further feeding injury to the tree, but the old tent will remain visible.
Of course, landscapers could choose to let the problem take care of itself, as the fall webworm does not present the same dangers to trees that the spring tent caterpillars do.
‘We have many natural parasites and pathogens of fall webworm that will bring these infestations under control,? Smitley wrote. ‘Places with lots of fall webworm this year may not have as much next year. Outbreaks usually last two to three years.?
Jacobsen also noted that a colder winter could help to stave off an increase next year.
‘This past winter was very mild, and we are seeing the effects of that now,? he said.
Tulip said those interested in learning more about the fall webworm can call her at the Buildings and Grounds Department, at 391-0304, ext. 133.
She is also offering advice on how to find and deal with Gypsy Moth eggs, which usually hatch in May, and are considered another one of those springtime pests that are similar in size to the tent caterpillar.