Intraspecific nest parasitism in the sand waspStictia heros (Fabr.) (Hymenoptera: Sphecidae)

Two forms of intraspecific nest parasitism are described for the neotropical sand waspStictia heros (Fabr.). Females behaving aggressively made aerial attacks on prey-laden females as they approached their nest for provisioning. Attacks resulted in prolonged grappling on the sand, and the relative sizes of the contestants influenced final possession of the prey. Also, the probability that returning females were attacked was directly related to the size of the prey being delivered. Females displaying marauding behavior entered the nests of other females, removed prey, and deposited it in their own nest. Females usually raided nests that were near their own nest and tended to concentrate raiding attempts on nests that previously yielded prey. We also describe the behavior associated with the delivery of hunted prey and examine possible interrelationships between wasp size, prey size and hunting trip duration.