Lindgren, D.L., & Sinclair, W.B. 1944 Relation of mortality to amounts of hydrocyanic acid recovered from fumigated resistant and nonresistant citrus scale insects.. Hilgardia 16(6): 303-315.

Notes: Fumigation of nonresistant and resistant red scale (Aonidiella aurantii) indicates that the resistant race, with the various concentrations and exposures tried, is more difficult to kill than the nonresistant. Any added increment of either concentration or exposure has a greater effect on the kill of the nonresistant scale than on the others.