WOOLLY ALDER APHID
CAUTION: This information was developed for North Carolina and may not apply to other areas.
Winged woolly alder aphids are black to gray with a 10 mm wingspan. The
abdomen is covered with white, fluffy wax. Plump, gray, wingless aphids on maple
leaves are about 2 mm long and are concealed beneath dense,
white, waxy strands. On alder, wingless aphids have short, dense strands
which are divided into small squares. Each egg is covered with a white woolly
coat. Nymphs resemble wingless adults but are somewhat smaller.
Eggs of the woolly alder aphid overwinter in cracks and crevices on the bark of silver maple trees. In spring, nymphs emerge and begin feeding at the midvein on the underside of new leaves. All the young are females which give birth to live young and produce large colonies. Their feeding on the foliage causes the leaves to curl and pucker. In late May through July, the new progeny develop wings and fly to alder trees. Once they reach alders, these aphids feed on twigs and begin reproducing sexually. The colony becomes enveloped in white, fluffy wax and is soon composed of aphids in all stages of development. In the fall, some aphids mature into male and female forms, return to maple trees and mate. Each mated female lays only one egg, which is the overwintering stage. The aphids also overwinter in colonies on alder where they reproduce by giving birth to live young females only.
Insect control on shade trees is frequently not practical because of high treatment cost and limited damage by the pests. Often large trees are infested and satisfactory treatment requires the services of a commercial operator. Because of the heavy wax filaments covering the bodies of the aphids and the "pockets" produced by the feeding of aphids on the leaves of maple, good coverage and penetration are needed for adequate control. For best results, spray maple trees when the production of honeydew is first noted and repeat as needed to about June 15. For good control, use two applications at weekly intervals. Following are some insecticides labeled for aphid control. See NC Agricultural Chemicals Manual below for additional choices.
|bifenthrin||(Talstar)||10% wettable powder|
|imidacloprid||(Merit) & other||follow label instructions|
|*insecticidal soap||various||follow label instructions|
|fluvalinate||(Mavrik)||23% aquaeous flowable|
|*malathion||56% emulsifiable concentrate|
* Suitable for home use.
Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage and examine a current product label before applying any chemical. For assistance, contact an agent of the North Carolina Cooperative Extension Service in your county.
© 2001 NC Cooperative Extension Service
Prepared by: James R. Baker, Extension Entomologist. Photos by J.R. Baker, forestryimages.org.
ENT/ort-06 May 1994 (Revised) 2001
Web page last reviewed January, 2011 by the webperson.