Landscape and Nursery - Pine Bark Adelgid

The following is an article on Pine Bark Adelgid, a pest of white pine that you should start scouting for this time of year.


Photo by Petr Kapitola, State Phytosanitary Administration, Bugwood.org

Pine Bark Adelgid, Pineus strobi, is a common pest on eastern white pine. This insect is found throughout the native range of eastern white pine and sometimes on Austrian and Scots pines. The species is native to Europe, and was unintentionally introduced into the United States on nursery stock in the early 1900s.

The overwintering life stage is the mature female, who begin to lay eggs in early spring. Winged and wingless females develop from these eggs. This species reproduces by parthenogenesis (without the need of males for fertilization). The winged forms fly to spruce where they lay eggs, but nymphs from these eggs do not complete their development, and eventually die. The wingless forms continue to develop on white pine, feeding on bark. If abundant, the pine bark adelgid may decrease the health of a small eastern white pine. Five generations are produced each year in the Mid-Atlantic States.

From a distance, the trunks of heavily infested white pines often appear to be whitewashed. When the white "wool" is pulled away from a mature pine bark adelgid, a black teardrop-shaped insect with short legs may be revealed. Examine the bases of eastern white pine buds on small plants from late March through April for the presence of this insect. Apply horticultural oil as a dormant treatment. Formulations of acetamiprid, bifenthrin (Bifenthrin Pro Multi-Insecticide, Talstar F, Talstar Lawn & Tree Flowable, and TalstarOne Multi-Insecticide only), chlorpyrifos (Dursban 50W only), cyfluthrin and imidacloprid, deltamethrin, horticultural oil, imidacloprid, insecticidal soap, oxydemetonmethyl, and tau-fluvalinate are labeled for management of this pest. Apply according to label directions from late April through May when these insects are active, if indicated. Use a high-pressure spray of water to wash infestations off the trunks and branches of large eastern white pines.

Written by Gregory Hoover in April 16, 2004 edition of Ornamentals Hotline from the University of Delaware Cooperative Extension. Recommendations were added from the Penn State Woody Ornamental Insect, Mite, and Disease Management Website.