Gypsy moth outbreaks reported around Lower Peninsula, leading to tree defoliation

Gypsy moth populations appear to be on the upswing in Lower Michigan. (photo courtesy of Michigan Department of Natural Resources)
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LANSING (WJRT) (6/12/2019) - Populations of invasive gypsy moths are beginning to swell this summer in parts of the Lower Peninsula, according to the Michigan Department of Natural Resources.

The pest, which eats leaves off trees until they are bare, appears to be on the upswing. It caused widespread defoliation around Michigan in the 1980s and 1990s.

The leaf-eating caterpillars are hairy, up to 2 inches long and have a pattern of blue and dark red spots. A large population was reported in 2018 and their eggs are hatching this year.

The heaviest defoliation in Michigan has been reported in Barry, Ionia and Washtenaw counties. Smaller pockets of gypsy moth activity are occurring around the southern Lower Peninsula.

Residents likely will notice defoliation through July, but the DNR says nobody should worry about lasting damage to their trees if they get attacked by gypsy moths unless they get damaged several years in a row. Most trees will grow a second set of leaves over the summer.

“Gypsy moths rarely kill trees in Michigan,” said James Wieferich, a DNR forest health specialist. “Only stressed trees suffering from problems like drought, old age or root damage are at high risk. In most cases, gypsy moth caterpillars are more of a nuisance in residential areas than in the woods.”

Gypsy moth populations swell most often following dry summers, such as the last three years. Their populations may remain high for a few years before dropping off naturally.

The DNR has used a natural fungus and virus to combat gypsy moths in the past.

Proactively promoting tree health is the best way to ward off any lasting damage from gypsy moths.

“Water trees regularly and avoid damaging the roots and bark,” Wieferich said. “That goes a long way in helping trees fend off the effects of defoliation.”

Residents who notice a gypsy moth outbreak on their trees can fight back by spraying the trunk with a mixture of dish soap and water or scraping caterpillars into a bucket of soapy water.

Some natural sprays that kill gypsy moths are available on the market.