none Host discrimination, i.e. the ability to distinguish unparasitized hosts from parasitized ones, and to reject the latter for egg laying is present in many parasitic wasp species. This property is classically considered as an example of contest competition, and is supposed to have a number of functions. Apparently the marks used for recognition are specific. Multiparasitization is the best strategy when hosts are scarce and the egg supplies of the parasitoids are not limited. Interspecific host discrimination is not an ESS. Superparasitization within one species would have selective advantage if the number of unparasitized hosts is small. The hypothesis is tested that the egg laying strategy of wasps is dependent on the number of conspecifics that is searching simultaneously for hosts, since this determines the chance that a parasitized host encountered by a wasp is parasitized by herself. It is shown that host discrimination cannot be regarded as a case of contest competition. Other aspects of superparasitization, related to interference and population regulation, sex allocation and encapsulation are briefly discussed. Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Host parasite relationships Drosophila (Drosophilidae); Hymenopteran parasites; Asobara & Leptopilina heterotoma; Host discrimination & superparasitization roles, review; Host recognition; Host discrimination by Asobara & Leptopilina (Hymenoptera), role Asobara rufescens; Asobara tabida (Braconidae ); Leptopilina heterotoma (Eucoilidae ); Dipteran hosts; Drosophila; Host discrimination & superparasitization roles; Host recognition; Host discrimination role; Drosophila (Diptera) host, review