Dogwood sawfly

Dogwood sawfly, Macremphytus testaceus Norton, has been detected in Whatcom County, WA recently and has also been found in King County in Bellevue in years prior. According to Sharon Collman at WSU Extension, it completely strips plants at the end of season. It may become a problem, in particular, on plantings of red osier dogwood. The larvae didn't show up until late season just before late August. In that particular infestation, the larvae were all on the top leaves and could be seen in outline from the backlighting of the sun through the leaves. In another site, the tree had a heavy infestation which was pruned off that same year. Larvae did not return the next year. Parasites have been found associated with the larvae found in King County.

The larvae leave the dogwood to pupate and will burrow into soft wood, and possibly soil, so house siding near a plant may be pitted with pupating chambers. Further damage may occur to structures from woodpeckers seeking to feed on the overwintering insects.

There is an effort to identify the extent of this recently introduced insect pest. Impact on both native landscapes and dogwoods produced in nurseries could be significant. If dogwood sawfly infestations are found, please contact Eric LaGasa, Washington State Department of Agriculture, ELaGasa@agr.wa.gov.

Photo: Jill Cotton

More information can be found at the following link:

Dogwood Sawfly Fact Sheet: Penn State Woody Ornamentals Integrated Pest Management.

Page last modified 11/7/07