Quarterly Journal of Microscopical Science, Vol s3-96, 181-191, Copyright © 1955 by Company of Biologists

Further Studies of the Third Instar Larval Cuticle of Calliphora erythrocephala

¹ Department of Zoology, Cambridge; now at the Science Service Laboratory, Department of Agriculture, London, Ontario

The penetration and reduction of ammoniacal silver nitrate solution in the epicuticle of the larva of Calliphora was studied. The epicuticle of the third instar larva is more permeable over the muscle insertions and cuticular sense organs. This finding is related to their development at the previous moult.

A surface layer of orientated wax is not present. Proteinaceous and fatty materials from the feeding medium modify the properties of the cuticle surface. Chloroformmethanol extracts a soft light brown acidic lipide from the protein of the epicuticle after contaminants from the medium are removed.

The water loss from larvae and puparia of different ages and after various treatments was studied. Young puparia recover from abrasion but larvae do not. An hypothesis that waxy substances are liberated on to the surface of the puparium during hardening and darkening of the cuticle is presented and discussed.

The pore canals penetrate the endocuticle until they are cut off from the epidermis by the development of the prepupal cuticle just after the puparial contraction. An inner endocuticle in which pore canals were absent was not found. The structure of the pore canals as shown by phase contrast examination is discussed. The pore canals are three times more concentrated in the lateral regions than in the dorsal or ventral regions.

The oenocytes go through a secretory cycle during puparium formation similar to that occurring before moulting of the larva.