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Males of aculeate Hymenoptera differ in the behavioural adaptations employed to locate and secure mates. The ecological and evolutionary bases of these differences are explored in this paper. Male bees and wasps search for females by patrolling widely within emergence-nesting areas or within patches of flowers attractive to conspecific females, or by waiting at landmarks, at specific emergence sites, or at nests. Nest dispersion, flower distribution, the type of female mating system and the nature of male-male competition appear to be key factors in determining the mate-locating behaviour of'males. Of special interest in multiple-mating by females, which may be an evolutionary response to the costs of attempting to resist copulation in certain situations. When polyandry occurs, males are under selection pressure to be the last male to copulate with a female prior to oviposition if sperm precedence occurs. In species in which females mate just once, a selective premium is placed on being the first male to reach a virgin female. In either case, because receptive females are a limited resource, there is intense competition among males for access to the resource. The density of competitor males may play an important role in determining whether holding a relatively restricted territory is preferable to the strategy of patrolling widely at various sites which may have females. Territoriality is practiced by males of several species of aculeate Hymenoptera when the number of male competitors is relatively few in number and the distribution of emergence sites or foraging areas of females is clumped in space.

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Gordh and DeBach: Courtship in Aphytis lingnanensis Group Other cultures determined conspecific with the standard culture of A. linqnanensis include R•-72-32, R-72-33, R-72-55, and R-74-5. (R-cultures refer to the year of importation-e.g., 1972, 1974 and the lot number. Aphytis coheni is a sibling of lingnanensis. Notes on each culture are on file at the Division of Biological Control, Riverside.) Cultures .R.-73-93 and R-73-94 were imported from field collections of parasitized Chrusomphalus bifasiculatus Ferris (6/26/1973) on Lithocarpus cdulis, and Aonidiella taxus Leonardi (6/26/1973) on Podocarpus macrophylla, respectively. Crossing tests indicated that the cultures: were: conspecific. Crossing tests among cultures R-73-112 (imported 7/9/1973 from Aonidiella iaxus on Podocarpus macrophylla) and R•-73-113 (7/9/1973 from Chrysomphalus bijasiculatu« on Lithocarpus edulis) indicated that they were conspecific. Crossing tests among R-73-93, R-73-94, R-73-112, R-73-113, and R-73-114 revealed a sex ratio comparable to homogamic crosses (55 to 65 percent female.s) ; thus all of these cultures were considered conspeeific, All of these cultures came from the same general area of Kyushu in southern Japan. Morphologically, adults of all five of the latter cultures were similar to Aphytis melinus, A. holoxanthus, and A. fisheri. Consequently, crossing tests were conducted among those cultures. 'I'ests revealed that the Japanese cultures were reproductively isolated from A. fisheri and A. holoxomth.us. Results of crossing tests with A. melinus were unusual. When males from the J apanese cultures were crossed with females of A. melinus, the sex ratio of the F 1 approximated 50 percent female, which indicated reproductive compatibility. Reciprocal crosses produced less than 3 percent females in the F 1 generation.