Macremphytus tarsatus. Dogwood Sawfly, is a significant pest to dogwood (Cornus) species. Because the Dogwood Sawfly takes on several forms while in the larval stage, it may not be easy to identify. Even the first instars can devour small portions of leaves, with groups of them producing a skeletonized appearance to the leaves. However, the larger final instar can consume entire leaves, leaving only the tougher leaf midribs.
Dogwood sawfly’s host plants are dogwoods (Cornus species), particularly Cornus racemosa, gray dogwood and, just slightly less so, Cornus sericea, the osier dogwood. The larval stages can cause extensive leaf damage over the course of the summer, but there is little risk of plant mortality since defoliation is accomplished late in the growing season.
Upon hatching the young larvae devour leaf portions, but as they enlarge, they consume even more of the leaves, leaving only midveins of the leaves. Overwintering in wooden structures may result in damage to those structures by woodpeckers searching for the grown larvae.