Nature 249, 179 - 180 (10 May 1974); doi:10.1038/249179a0

Is polymorphism in two-spot ladybird an example of non-industrial melanism?

B. R. BENHAM^*, D. LONSDALE^† & J. MUGGLETON^‡

^*Science Department, Bolton Institute of Technology, Bolton, Lancashire
^†Cryptogamic Botany Laboratories, The University, Manchester
^‡Department of Zoology, The University, Manchester

THE polymorphism exhibited by the two-spot ladybird, Adalia bipunctata Linn., in which specimens have a red ground colour and black spots (the typical morphs) or a black ground colour with red spots (the melanic morphs) is a well known phenomenon. The reasons for the existence of this polymorphism, however, are not well understood. Analogy to the situation in some melanic Lepidoptera, such as Biston betularia Linn.^1,2, is unacceptable as it would seem that selective predation by birds upon the morphs which blend less well with their surroundings would not operate upon A. bipunctata. Ladybirds are distasteful, have a distinctive scent, are warningly coloured and therefore are avoided by vertebrate predators^3,4.

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