McClure, M.S. 1979a Self-regulation in populations of the elongate hemlock scale, Fiorinia externa (Homoptera: Diaspididae); role of food quantity and quality.. Miscellaneous Publications of the Entomological Society of America 11: 33-40.

Notes: Studies revealed that survival, development rate and fecundity of F. externa were negatively influenced by its own density for two consecutive generations.