Studies of Predators of the Balsam Woolly Aphid Adelges piceae (Ratz.) (Homoptera: Adelgidae): I. Field Identification of Neoleucopis obscura (Hal.), Leucopina americana (Mall.) and Cremifania nigrocellulata Cz. (Diptera, Chamaemyiidae)

Abstract

The introduction of predators of the balsam woolly aphid, Adelges piceae (Ratz.), from Europe to the Atlantic Provinces of Canada was commenced in 1933 as a joint project of the Forest Biology and Entomology Divisions of Science Service and the Commonwealth Institute of Biological Control. Several species were released between 1933 and 1941 but only one, Neoleucopis obscura (Hal.), became established and its control value was insufficient (Balch, 1952). The project was continued in 1951 and several additional species have been established. Studies of these predators and their place in the control complex in Canada were undertaken and this paper is the first in a series on the subiect. It results from the necessity of rapid field identification of the various stages of all predators found. It deals with three closely related dipterous predators, two of which were introduced, N. obscura and Cremifania nigrocellulata Cz., the other, Leucopina americana (Mall.), being native to Canada. Similar descriptions of the other species with a key will be published later.