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SUMMARYWork on the nature of the factors selecting against the melanie morphs of Adalia bipunetata is reviewed, New data are presented showing that there is normally one generation per year in Great Britain and that the cyclical changes in morph frequency observed in Berlin may not occur in Great Britain.The roles of migration and selective predation in limiting the spread of the melanie morphs are discussed and evidence is presented to show that predation by birds on ladybirds occurs more frequently than previously supposed.In conclusion it is proposed that the melanie frequency of a population is the result of the interaction of a number of factors whose importance varies from locality to locality.

SUMMARYThe nature of the factors maintaining the colour polymorphism in Adalia bipunctata has been the subject of much discussion and in some populations a tendency for the melanic morphs to mate more frequently than the nonmelanics has been reported. The morph frequencies among mating pairs in wild populations of A. bipunctata in England have been scored and analysed in order to discover whether mating between morphs is a random process. Data from the literature are also analysed in the same way and the methods of analysis adopted by earlier workers are discussed. It is concluded that mating between morphs is frequency dependent so that it is the rare morph irs the population, regardless of colour, which mates more frequently. This appears to be a further method by which the polymorphism in this species is maintained.

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