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Common woolly aphids and adelgids of conifers

By R. W. Duncan

Introduction

The term "woolly" aphids or adel-gids is frequently used to describe any of a large number of aphids or aphid-like insects characterized by having a noticeable white waxy covering. A conifer-feeding woolly aphid, Mindarus abietinus and adelgids of the genera Adelges and Pineus are common through-out British Columbia and may be found feeding on the needles and bark or in twig galls (Adelges and Pineus only). Most native conifers are affected except cedars, cypresses and junipers. Many species of Adelges and Pineus alternate between a primary host (spruce), where they induce the formation of twig galls which form around and enclose the feeding nymphs, and a secondary host where no galls are formed and the nymphs feed externally. Mindarus and some species of Adelges and Pineus are confined to a single host and do not cause gall forma-tion. Damage caused by the differ-ent species of woolly aphids or adelgids includes chlorosis, stunt-ing and twisting of needles as well as galling and gouting of the twigs. Severe and chronic infestation may result in loss of foliage, growth reduction, or mortality.

For more information, see the Common woolly aphids and adelgids of conifers Forest Pest Leaflet in the Canadian Forest Service bookstore.