Egg laying activity of the slug Arion lusitanicus Mabille in Switzerland.

1.     Arion lusitanicus Mabille was found to lay more than 200 eggs per clutch with an egg volume between 11 and 34 mm³.
2.     The weight of adult individuals of A. lusitanicus varied between 3 and 27 g.
3.     The body weight of the slugs correlated positively with egg volume. However, there was no correlation found between body weight and the number of eggs per clutch, or between egg volume and the number of eggs per clutch.
4.     Clutch size decreased over the period of the investigation.
5.     Slug density was probably responsible for the differences observed in the reproduction parameters, measured at three different locations.