Cynipid Wasp

Since 2009 the island of Martha’s Vineyard has had significant reports of  Black Oak (Quercus velutina)  being attacked by large  populations  of a Cynipid Wasp, (Bassettia ceropteroides), family Cynipidae.  The intensity of these outbreaks has caused widespread mortality to black oaks with a particular pattern of attacking stressed trees, predominately mature trees that have suffered or had become predisposed by previous abiotic (environmental) or biotic (example – caterpillar defoliation) in previous seasons. Possible environmental factors include drought stress, storm damage (salt spray) and prior insect defoliation (fall canker work, spring canker worm, and winter moth.)

Read more from the Cape Cod Times

The Cape Cod Cooperative Extension has published a very informative info sheet on the Cynipid Gall Wasp problem.

View it here.

Previous reports of cynipid wasp oak mortality have occurred on Long Island, NY.

The wasp attacks the outer crown of black oaks indicating a preference for the soft new tissue of the previous seasons growth. Repeated attacks eventually result in tree mortality.

We are collecting data from arborists and homeowners who have had a professional diagnosis of this pest on their property. To report wasp damage download our survey and mail it to Polly Hill Arboretum, PO Box 561, West Tisbury, MA 02575.  (please note the Arboretum does not provide diagnostic services)

PICTURES OF BLACK OAKS OF CHAPPAQUIDICK