Cankerworms Causing Defoliation in Southern Maryland Trees

Most Affected Trees Expected to Recover Fully

ANNAPOLIS, MD – An infestation of cankerworms have eaten the leaves off of many trees in Anne Arundel and Prince Georges counties; however, entomologists with the Maryland Department of Agriculture expect most trees to survive the defoliation without difficulty.

“These green caterpillars are often mistaken for the much more destructive gypsy moth,” said Forest Pest Management Program Manager Bob Tatman, “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 have exhibited small sometimes three-year outbreaks around Maryland, the last one was in 2012 to 2015 in Charles, Calvert, St. Mary’s and Washington Counties.  The outbreaks are difficult to predict and more likely to be gone after the second year than to persist. Residents who are concerned about the cankerworm’s impact on high-value trees may want to consider insecticide treatment by a licensed pesticide applicator. In addition, watering and fertilizing may also help keep trees healthy.

For a list of licensed pesticide applicators near you, click here.

To see the difference between gypsy moths and cankerworms, click here.

For more info on Maryland Forest Pest Management, visit the program’s website or call (410) 841-5922.

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