Stimmel, J.F. 1979a Elongate hemlock scale, Fiorinia externa Ferris (Homoptera: Diaspididae).. Regulatory Horticulture (Pennsylvania Department of Agriculture) 5(1): 13-14 (Ent. Circ. No. 36).

Notes: Hosts, distribution, identification, life history, damage and control of this serious pest of hemlocks.