Abstract
The external sculpturing of the egg of M. calthella L. appears after the egg has been laid. Immediately after oviposition, the external surface of the egg is smooth, being covered with a viscous material. During the hour following oviposition, this material is locally raised up, forming club-like structures that remain perpendicular to the egg surface. These club-like structures result from exudation of a substance produced by the oocyte. The external layers of the egg and their ornamentations do not constitute a true chorion because they are not secreted by the follicle cells.