The taxonomic value of characters provided by male Coccoidea is reviewed in relation to traditional classifications based on the female. Numerical methods based largely on principal component analysis are applied to the classification of some Diaspididae and the various techniques are compared and evaluated.

A quantitative comparison of the classifications of 24 species of male Diaspididae by principal component and principal coordinate analysis was extended to allow the comparison of classifications based on selected subsets of the 101 available characters. It was shown that subsets of 25-28 characters could be chosen numerically and used to construct classifications that resembled very closely the classitication based on the reference set of characters. The conclusions are discussed in relation to other views on character-weighting and in relation to classifications of the Diaspididae based on traditional taxonomic characters provided by the females.

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SYNOPSISAn account is given of variation in 18 characters in a number of females taken from a homogeneous population of Coccus hesperidum. The latent roots and vectors obtained from the correlation matrix of these characters are discussed and an interpretation of the vectors is given.