The external morphology of all stages ofC. ischnochelesis described, particular attention being paid to the chactotaxy. A comparison is made withC. tetrachelatusand the constancy between most of the chaetal series proves useful in the separation of the nymphal stages. Certain chaetal series, however, appear to be potentially important at both the specifie and generie levels of classification and the significance of these wider applications are briefly discussed. A precise study of the chactotaxy and its variations during post‐embryonic development indicates the existence of regressive evolution (i. e. neoteny) and it is for this reason that the adults of certain species possess, at least partially, a chaetotaxy which is characteristic of the nymphs of other species. The life history, based on a quantitative sampling technique, is described. Eggs are carried from June onwards and protonymphs appear in their highest numbers during July‐September. Mainly deutoand tritonymphs overwinter and maturity is reached the following June