DETROITS LAKE, Minn. - The city is being overrun, and not just by tourists flocking to beaches and bars. To a forest tent caterpillar, the lakes area is crawling with prime dining and real estate opportunities.
The caterpillars, typically 2 inches long, with blue or green longitudinal stripes and a white spot on each abdominal section, are common anywhere hardwood deciduous trees offer ample shelter and snacking.
This year, many people have noticed an increased population of the hungry little socialites, which are known to live in large groups and strip trees of their foliage through constant consumption.
"They cycle generally every eight to thirteen years," Jeff Hahn said. Hahn is an Extension Entomologist for the University of Minnesota.
"Ten years is normal in the forest setting," Marty Wiley, Forestry Supervisor at the Detroit Lakes office of the Minnesota DNR, said. "I can't remember in my 10 years seeing anything this extreme, so it must be the tenth year," he added with a laugh.
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The population ebbs and flows over a reasonably regular cycle, climaxing in an abundance that typically lasts three years.
"If you see them this year, you'll likely see them next year," Hahn said.
Usually forest tent caterpillars, known as Malacosoma disstria in scientific circles, consist of an inconspicuous population. When peak years hit, their presence quickly becomes obvious -- and, for some, annoying.
"The caterpillars chew on leaves, and they can potentially strip or defoliate trees," Hahn said.
Favorite local cuisine, according to Wiley, includes basswood and oak.
However, beyond a few weeks of ugly trees, area yards and forests have little to worry about.
"Trees can tolerate severe or even complete defoliation in a single year if they are healthy and vigorously growing," Hahn said.
Only several consecutive years of stripped leaves are enough to kill a strong tree. However, for trees already under strain from pests, disease, or drought, the caterpillars will have a more threatening impact.
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Forest tent caterpillars, commonly and mistakenly referred to as army worms, pose no threat to human life. Although their long hairs, or setae, might be irritating to sensitive skin, the bugs don't bite and are not poisonous.
Still, "they can definitely be a nuisance," Wiley said.
Hahn assured a reporter that the caterpillars "should be cocooning soon."
"By mid-July, you should see everything green up again," Wiley added.
That's right around the time that the caterpillars will emerge from their cocoons as nocturnal tan moths with short furry bodies - and the capability to lay 300 eggs at once.
"Most of the time when folks have them crawling on their steps or in their yards or on a favorite tree, people can pick them off," Wiley added, mentioning that brooms or soapy water can also be helpful.
Thressa Johnson is a reporter at the Detroit Lakes (Minn.) Tribune, which is owned by Forum Communications Co.
