BIONOMICS OF THE PEAR PSYLLA, PSYLLA PYRICOLA FOERSTER, IN THE OKANAGAN VALLEY OF BRITISH COLUMBIA

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Abstract
In the Okanagan Valley of British Columbia, the pear psylla, Psylla pyricola Foerster, develops only on pear. It overwinters in a variety of protected situations in or near pear trees, e.g., under bark scales, in ground crevices, occasionally under the bark of apple tree interplants in pear orchards, and even in such unlikely quarters as the nests of hornets. Four summer generations and an over-wintering generation occurred in 1961 and 1962. Development of the psyllid from egg to adult required 6 to 7 weeks in the cool weather of spring but only 4 to 5 weeks in midsummer. Heavy rains readily remove nymphs from leaves and twigs but cannot dislodge the firmly attached eggs. Adults have been noted clinging to leaves and twigs in winds of up to 55 miles per hour. Biological control of the pear psylla is affected mainly by two predators, the anthocorid bug, Anthocorus melanocerus Reuter, and the neuropteran, Chrysopa oculatus Say. Dormant oil sprays are detrimental to the anthocorid. There was a major migratory flight of the pear psylla in August and September and two minor migratory flights in late March and mid-June. Aitborne psyllids decreased in numbers with elevation.