Other Common Names
American Blight, Apple Root Aphid
Reddish-purplish with characteristic bluish-white woolly masses of wax on its body
Feeds principally on apple, also, pears, hawthorn, ash, alders, elms and oaks.
Usually overwinter on elms and the first generation is spent on that host. In early summer winged forms appear, they migrate to apple, hawthorn and related trees. Later in the season some migrate to elms, where the bisexual generation is produced and over wintering eggs laid. Other individuals migrate from the branches of the apple trees to the roots, where they produce gall-like growths. The root-inhabiting forms may remain there for a year or more, passing through several generations.
This aphid transmits perennial canker. It is more of a problem when pesticides have destroyed its natural enemies.
The larvae of Heringia calcarata
(Syrphidae) feeds on this aphid and is considered as a possible biocontrol (Short 2003
). Another biocontrol is the parasitic wasp, Aphelinus mali
.. There are others such as earwigs and predatory mites.
Native to North America. It has been accidentally introduced into other areas.