Amphidasis betularia (L.), and its melanic varieties

Summary

OfAmphidasis betularia (L.) three forms occur in nature: the type, the true melanic varietydoubledayaria Mill., and a well characterised intermediate form, the occurrence of which is due to a single gene, which is dominant to the gene for “type” but recessive to “melanic.” The intermediates are especially characterised by the white dots on black ground of the abdomen.