Wooly apple aphid, Eriosoma lanigerum (Hausmann) (Homoptera: Aphididae), damage to apple roots. Photo by J. W. Stewart.
Common Name: Wooly apple aphid
Scientific Name: Eriosoma lanigerum (Hausmann)
Order: Homoptera
Description: Aphids are reddish-purplish, wingless or winged and covered with woolly, bluish-white wax masses.
Several other aphid species (Paraprociphilus spp., Eriosoma spp., Stegophylla spp.) produce large quantities of woolly wax filaments and infest leaves of alders, elms and oaks. At certain times during the summer, infestations can become noticeable on host plants such as Arizona ash in central Texas. Masses of woolly aphids infest the undersides of leaves on terminal growth, causing leaves to turn pale green and curl.
Life Cycle: Simple metamorphosis; parthenogenic. Winter is spent in the egg or young nymphal stages underground in root galls, and as adult egg-laying females on the branches and trunks of host plants. Eggs are laid in bark cracks on elm in the fall and hatch in early spring. Wingless nymphs feed on new growth and twigs for two generations (May and June), producing winged forms that fly to other host plants (apple, hawthorn and mountain ash). There, they feed on wounds on trunks and branches and move to the root zone. In summertime, females give birth to live young (parthenogenesis). Wingless males are produced in the fall and mate with wingless females, each of which lay a single overwintering egg.
Habitat and Food Source(s): Aphids become noticeable because of the woolly wax masses on wounds of the trunk and branches on apple, elm, hawthorn, mountain ash, pear and quince. Underground, aphids cause large knots on roots on apple trees. Heavily infested trees become stunted and may die. Rootstock of all but a few apple varieties is susceptible to attack. Woolly apple aphids have become a problem in areas of Texas where dwarf apple varieties have been planted using susceptible root stock. Aphids can be preserved in alcohol, although the waxy masses will dissolve. Waxy masses can be preserved by freezing infested leaf specimens and storing them dry in a vial or small box.
Pest Status: Occurs on apples with susceptible rootstock or susceptible varieties; medically harmless.
For additional information, contact your local Texas A&M AgriLife Extension Service agent or search for other state Extension offices.
Literature: Johnson & Lyon 1988; Metcalf et al. 1962.