A multivariate analysis of postembryonic growth in two species of Ectobius (Dictyoptera: Blattidae)

Principal component analyses of postembryonic changes in the dimensions of over 70 skeletal structures were carried out in Ectobius lapponicus (Linn.) and E. panzeri Stephens. The results are interpreted as four or five orthogonal patterns of growth, of which the major constituent is very simply related to the set of independently definable allometric growth ratios. The methods of analysis are discussed in relation to other multivariate techniques and their uses in the quantitative description of growth and metamorphosis are indicated.