Beirne, B.P. 1975 Biological control attempts by introductions against pest insects in the field in Canada.. Canadian Entomologist 107(3): 225-236.

Notes: This is an analysis of the attempts to colonize at least 208 species of parasites and predators on about 75 species of pest insects in the field in Canada. Carulaspis visci, Lecanium tiliae, Lepidosaphes ulmi and Phenacoccus aceris were among the target species discussed.