Embryogenesis of Xyleborus ferrugineus (Fabr.) (Coleoptera, Scolytidae). I. External morphogenesis of male and female embryos.

A description of the external morphogenesis of male and female embryos of X. ferrugineus, derived from in vivo observation, is presented here. The embryogenesis of this beetle is typical of the Coleoptera, and is also similar in most respects to the generalized insect plan. Observed unusual aspects of X. ferrugineus embryogenesis include the precocious formation of primordial g/rm cells and their temporary exclusion from somatic blastoderm; the precocious in situ delineation of gnathal metameres, the closing of the gastral groove beginning at both ends and proceeding towards its middle, the formation of several paired lateral amnio-serosal folds, the formation of cellular processes between the amnion and serosa, and the absorption of the thoracic limbs to produce an apodous larva. The embryonic developmental picture provided here, and the previously established means of rearing X. ferrugineus in controlled laboratory culture jointly provide a promising basis for the further use of this insect in developmental studies.