Origin:
This species is native to Europe, but was first detected in North America around 1900. It now is found throughout eastern Canada and northeastern U.S., as well as along the Pacific coast in Oregon, Washington, and British Columbia.
Biology:
This adelgid feeds on fir trees in the genus Abies, and severe infestations on the stems will cause the needles to change color to rust red and the tree may then die. Periodically extensive die-off of forest trees will occur. The saliva of the insect contains a chemical that causes swelling and twisting of the plant stems, a condition called “gout disease”, resulting in reduced flow of nutrients in the cambium layer. Only females exist in the populations and all reproduction is asexual by parthenogenesis. There may be several generations each year and nymphs will overwinter. Eggs are deposited on the stems and twigs and the first nymphs will move about to new places on the tree, and then settle down to feed once a suitable location is found. Masses of white cottony wax will cover the aphids.
Identification:
Identified chiefly by the host plants (firs) and the presence of the white masses of wax on the bark of twigs and stems. The insect itself is oval, black, and with very short legs.
Characteristicts Important to Control:
Biological control by predators or parasites appears to be lacking for this species. Winter applications of dormant oils will help to kill overwintering nymphs and oils applied thoroughly to the wax masses during warm months will also help to control the problem. If contact insecticides are used a surfactant to help break down the wax and allow penetration of the water based spray will be helpful.
