Geier, P., & Baggiolini, M. 1950 Quelques observations sur la biologie de Pericerya purchasi Mask. au Tessin (Homopt. Margaroid). [Some observations on the biology of Pericerya purchasi Mask. in Tessin (Homopt. Margaroid.].. Mitteilungen der Schweizerischen Entomologischen Gesellschaft 23(2): 104-116.

Notes: History of the known distribution in Tessin of P. purchasi is discussed. Rodolia cardinalis, its predator, is reviewed. Host plants are listed and climatic and epidemiological factors are considered.