Mysterious White Caterpillars
Location: Southern New Hampshire
October 6, 2011 3:34 pm
We get these on our dogwood and ONLY our dogwood every early autumn. The seem to shed skins, curl into a ball and change colors to a yellow and blackish color. Then they seem to just disappear, leaving dark spots on the leaves where they were curled up.
You have Dogwood Sawflies, Macremphytus tarsatus. Though they resemble caterpillars, Sawflies are classified with the wasps and bees. According to BugGuide: “Young larvae are covered with a powdery white waxy coating. Mature larvae are yellow beneath with black spots or cross-stripes above.” The University of Minnesota Entomology website has a very informative pdf on the Dogwood Sawfly and the Penn State Woody Ornamental Integrated Pest Management web page states: “Dogwood Sawfly, Macremphytus tarsatus, 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.”