“…On few occasions, and these apparently exceptional, has Pentatrichopus fragaefolii been found to infest this host under natural conditions (Massee et al, 1938;Dicker, 1952a). There are numerous reports, however, that F. vesca may be readily infested artificially or when May, 1962] Schaefers-Allen : Strawberry Aphids 397 the host is removed from its natural habitat (Massee, 1935;Hodson, 1937;Thomas and Jacob, 1940;Greenslade, 1941;Hille Ris Lambers, 1953). Hille Ris Lambers suggested that the conditions of relative humidity under which the plant grows are responsible for a high mortality of the aphids at the time of molting.…”