Abstract
The preferences of Hadena bicruris for oviposition into pistillate plants of Melandrium album were observed in the Botanical Garden of the University of Nijmegen. Statistical analysis showed that each night most eggs are deposited on certain plants. Second-day flowers receive less eggs than first-day flowers. Flowers containing an egg have a lowered propability of receiving a second one. They have a “mark”, which functions only one night. This prevention of superparasitism, unique for Lepidoptera, is of survival value for the moth species.