Cankerworms Causing Defoliation in Southern Maryland Trees

ANNAPOLIS, MD (May 10, 2012) – An infestation of spring cankerworms have eaten the leaves off of many trees in Charles and St. Mary’s Counties  in Southern Maryland; however, entomologists with the Maryland Department of Agriculture (MDA) expect most trees to survive the defoliation without difficulty.

“These green caterpillars are often mistaken for the much more destructive gypsy moth,” said MDA 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 and many of the leaves have already started to grow back.”

Cankerworms are native insects that have exhibited small one- or two-year outbreaks around Maryland, the last one was in 2007 in Anne Arundel and Cecil 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.

More information on cankerworms, gypsy moths, and other forest pests can be found at the Forest Pest Management website:  www.mda.state.md.us/go/cankerworm.php or by contacting MDA’s Forest Pest Management office at (410) 841-5922.  A list of licensed pesticide applicators can be found at www.mda.state.md.us/plants-pests/pesticide_regulation/pesticide_db.php