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In the late 1950s, early 1960s, Maine and surrounding regions experienced an outbreak of the pine leaf aphid (or adelgid). The population progression began about 1955, as indicated by tree growth reductions (2), a peak was reached about 1961, after which populations gradually regressed through the late 1960s. As a result of the outbreak, there was considerable growth reduction of white pine in some regions and scattered tree mortality. Among the many observations on the insect made during the outbreak were (a) the aphid was abundant in only certain portions of Maine and remained uncommon in the remainder of the state, and (b) in those regions where the insect was abundant, some stands of pine suffered relatively severe damage while others were largely unaffected. This study sought to provide explanations for differences in the abundance of aphids throughout the state and the varying amount of damage between stands. Information gained in a study of this sort is useful in explaining the distribution and abundance of the insect and in suggesting silvicultural procedures designed to increase resistance of stands to insect damage.
Maine Agricultural Experiment Station
forest pests, Adelgidea
Forest Biology | Forest Management
Dimond, J.B., and R.H. Bishop. 1968. Susceptibility and vulnerability of forests to the pine leaf aphid, Pineu pinifoliae (Fitch) (Adelgidae). Maine Agricultural Experiment Station Bulletin 658.