Aphids feed in clusters and generally prefer new, succulent shoots or young leaves. Some species, known as wooly aphids, are covered with white, waxy filaments, which they produce from special glands.
Certain ants sometimes protect colonies of aphids. The ants gather aphids or their eggs and keep them through the winter in their nests. In spring, the ants transport these aphids to food plants where they protect them from enemies and at intervals transport them to new plants. For payment, the ants collect honeydew, a sweet sticky substance which aphids secrete as a waste product.
A sticky glaze of honeydew may collect on lower leaves, outdoor furniture, cars, and other objects below aphid feeding sites. Honeydew coated objects soon become covered by one or more brown fungi known as sooty molds. Crusts of sooty mold are unsightly on man-made objects, and they can interfere with photosynthesis in leaves.
Black or gray with long legs; found most commonly on white pines. This is a common pest of eastern white pines. Severe infestations reduce the growth and may even kill small trees. Colonies occur most commonly on twigs and stems where the bark may be killed in patches. Needles and twigs are sometimes completely covered with sooty mold. Their eggs are laid in lines on needles. They may hatch when infested white pines are brought indoors as Christmas trees.
Green or pink with black legs. A widespread and common pest of all cultivated roses, this species may also damage pyracantha. Stems, buds, and young tender leaves are damaged.
Ash gray with black spots. Nearly 1/2 inch (14 mm) long including the legs, this is our largest aphid species. It attacks willow, maple, elm, oak, birch, and several other common shade trees. It feeds on the bark of twigs and small branches. Bees, wasps, and flies are attracted to the honeydew they secrete.
Pale yellow-green in color. This species attacks dozens of different hosts including aster, catalpa, crocus, dahlia, English ivy, iris, lily nasturtium, pansy, rose, snapdragon, tulip, and violet, as well as many garden vegetables and some fruit trees. It is capable of transmitting over 100 different plant viruses.
Shiny dark brown with short cornicles. Common and widespread on chrysanthemum where they cause stunted growth and slightly curled leaves.
Plump and blue-black, but completely covered with white waxy filaments. Silver maple is the primary host, but they migrate to alder in mid-summer, then return to silver maple in late fall. This aphids is not particularly injurious to either host, but it becomes a nuisance when waxy filaments accumulate under heavily infested trees.
There are many other aphid species, some of which produce galls. Included in this group are Witchhhazel Cone Gall Aphid, Spiny Witchhazel Gall Aphid, and the Elm Cockscomb Gall Aphid.
Throughout United States.
Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Alan L. Grant, Dean, College of Agriculture and Life Sciences; Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.
May 1, 2009