[Structure of the larval integument of goat gadflies].

The structure and development of the integument of Przhevalskiana silenus during the different larval stages are described. The endocuticule of the 1st instar larvae is closely indented with the hypodermis. The indentation is not strong in 2nd-instar larvae and disappears in the third-instar completely. Thin plasmatic strings pass through the endocuticule of the 1st and 2nd-instar larvae. In the 3rd-instar larvae many canals are found in the endocuticule, which probably are pore-canals as described in investigations of other authors. These canals allow transport of substances from inside to outside and vice versa. The cuticular surface of the 2nd-instar larvae shows characteristic spines which might be an additional help for fixing in the hosts tissue during the stationary stages. These spines are missing on migrating larvae.