MacPhee, A.W., & MacLellan, C.R. 1971 Cases of naturally-occurring biological control in Canada.. Biological Control. Plenum Press New York & London 511 pp.

Notes: [Proceedings of an AAAS Symposium on Biological Control, held at Boston, Massachusetts December 30-31, 1969.] Lecanium coryli and Lepidosaphes ulmi are mentioned as targets of biological control.