Parthenolecanium quercifex

I recently visited a commercial landscape that had 5” – 6” DBH bur oaks (Quercus macrocarpa) with their newly expanding leaves speckled with clear, sticky honeydew. Twigs and branches had a dark, dingy patina owing to black sooty molds colonizing honeydew in the past indicating the problem was not new.

I recently visited a commercial landscape in southwest Ohio that had 5” – 8” DBH oaks (Quercus spp.) with leaves covered in clear, sticky honeydew. A close examination of one of the sticky oaks revealed a moderate infestation of Oak Lecanium Scale (Parthenolecanium quercifex, family Coccidae (Soft Scale Insects)).