This introduced pest is a serious threat to species of hemlock trees in the eastern U.S. Females deposit their eggs in clusters of 100-300 eggs on the undersides of the foliage, and then cover the eggs with masses of white wax that give the insect its common name and provide a distinctive character for ID. Eggs hatch in the spring and this first stage is mobile, while the second instar nymph settles down to feed at one location. The adults are winged and capable of flying, but reproduce only asexually (parthenogenesis), as they would require species of hemlock not found in North America for sexual reproduction. There are 2 generations each year. As the insects feed they may inject a toxin that causes defoliation and possible death of the tree several years later.
Insecticidal oils can be applied to infested leaf surfaces to coat and smother the feeding insects or eggs, but it must be thorough and the undersides of the foliage are especially important. Many natural and synthetic active ingredients are labeled for use on whitefly, and a systemic that can be applied to the soil may be effective, moving the active ingredient up and into the foliage where it is ingested by the feeding insects.