Asian woolly hackberry aphids are distinctive insects. A covering of thin bluish-white waxy filaments causes these small sap-feeding insects to standout on foliage (Figure 1). They can look like large wet snowflakes, especially as they drift through the air (Figure 2). This aphid has another dimension: excretion of large volumes of sticky honeydew. Foliage and branches of infested trees, as well as surfaces beneath them, become wet and shiny. These surfaces ultimately may turn black from the growth of sooty mold fungi.
The insect has been abundant in Todd County; noticeable numbers of woolly aphids also have been reported from Webster and Marshall Counties. Several species of woolly aphids occur in Kentucky; it is not clear which ones were involved in the latter sightings.
Woolly aphids do not appear to cause significant injury to otherwise healthy trees. However, dripping honeydew and subsequent accumulations can be objectionable in some situations. Honeydew may attract flies, bees, and wasps. Insecticidal soap has been used as a foliar spray to provide some control of the aphid, as well as in an effort to wash away the “dew.”
By Lee Townsend, Extension Entomologist