Woolly Alder Aphid
Hosts: Silver maple and alder
Evidence: Throughout early summer, look for white, wool-like waxy filaments on branches and stems of host trees along with conspicuous curled leaves. The presence of honeydew, ants feeding on honeydew, or development of sooty mold are commonly associated with aphid infestations.
Life Cycle: The insect overwinters on maple bark in the egg stage or on alder in tightly-clustered, wool-covered aphid colonies. Newly-emerged aphids settle on the midvein of new maple leaves. These aphids reproduce asexually, producing very large colonies. The winged generation that develops flies to alder in July. Several generations may develop on alder, accompanied by production of large amounts of white waxy material (a). Some of the migrants fly back to the trunk and branches of maples, where they mate and produce eggs, one per aphid. Others remain on the alder in the adult stage.
Management: The insect is usually of little significance, although the amount of white waxy material that accumulates may be troublesome and some of the infested leaves drop prematurely. The associated honeydew and sooty mold may also be annoying. Many predators of woolly alder aphids are known, including lady beetles, lacewings and, on alder, one of the few predaceous butterfly larvae, known as the Harvester (Feniseca tarquinius (Fabricius).
Figure a: E. Bradford Walker, Vermont Department of Forests, Parks and Recreation, Waterbury, VT
Drooz, A.T. 1985. Insects of Eastern Forests. USDA Forest Service Miscellaneous Publication 1426. p 80;
Johnson, W.T. and Lyon, H.H. 1991. Insects That Feed on Trees and Shrubs . 2nd edition. Cornell University Press. p 304-307;
Martineau, R. 1984. Insects Harmful to Forest Trees. Agriculture Canada Government Publishing Centre, Supply and Services, Ottawa. p 189;
Rose, A.H. and Lindquist, O.H. Revised by Syme, P. 1994. Insects of Eastern Spruces, Fir and Hemlock . Canadian Forest Service Publication. p 124 and 276.