Yust, H.R., & Shelden, F.F. 1952 A study of the physiology of resistance to hydrocyanic acid in the California red scale.. Annals of the Entomological Society of America 45(2): 220-228.

Notes: Nonresistant and resistant strains of the California red scale Aonidiella aurantii were studied to determine the nature of the physiological basis for variations in resistance to hydrocyanic acid. Susceptibility to hydrocyanic acid is associated with a high degree of dependence on heavy metal-containing enzyme systems for tissue oxygen requirements, whereas resistance to hydrocyanic acid is associated with a high degree of dependence on metal-free autoxidizable respiratory enzymes, possibly of the flavoprotein type.