Cankerworms attack trees in four Maryland counties

Cankerworms have devoured the leaves on trees in several Maryland counties, entomologists with the state Department of Agriculture said.

But they expect the trees—mostly in Calvert, Charles, St. Mary’s and Washington counties—to survive.

"These green caterpillars are often mistaken for the much more destructive gypsy moth," said Bob Tatman, manager of the department’s forest pest management program. "Their presence, coupled with the obvious defoliation, has led some local residents to express concern about what's going on. Trees experiencing defoliation due to cankerworms usually recover completely if they are not otherwise stressed."

Cankerworms are native insects that pop up every few years in Maryland. The last outbreak was in 2007 in Anne Arundel and Cecil counties. 

The outbreaks are difficult to predict and likely to be gone after the second year. Residents who are concerned about the cankerworm's impact on expensive trees may want to consider insecticide treatment by a licensed pesticide applicator. In addition, watering and fertilizing may also help keep trees healthy. 

READ MORE: The fall and spring cankerworm

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