To analyze morphological caste differentiation in social wasps, variable reduction methods, such as the comparisons of Mahalanobis distances and the scatter diagrams of canonical scores and the analysis of mean queen/worker ratio of each morphometric characters, could only show whether there are some differences between the castes or not. These methods, on the other hand, do not document major aspects of the nature of morphological caste differentiation; that is, whether morphological differentiations are allometric or non-size based is not shown.