Notes on the habits of the spider hunting wasps Trypoxylon lactitarse Saussure, 1867 and T-menkeanum Coville, 1982 (Hymenoptera: Crabronidae) in Costa Rica

摘要

Spider-hunting wasps Trypoxylon (Trypargilum) lactitarse Saussure, 1867 and T. (Trypargilum) menkeanum Coville, 1982 were studied at the Organization for Tropical Studies field station at La Selva, Costa Rica. The wasps nested in trap-nests with tube of 6.4, 8.0, or 9.5 mm diameter. Nest structure, cocoon morphology, and differences between male and female provisions are described. Brood cells of T. lactitarse were provisioned with 5 to 19 spiders and those of T. menkeanum with 4 to 24 spiders. Most spiders were immature Araneidae, especially Eustala sp., but several other families of snare-building and wandering spiders were also among the prey. Male brood cells were more frequent in small diameter nests and at the inner end of nests. Female cells were more frequent in larger diameter nests and near the entrance. Mating almost always took place in the nest immediately before oviposition, but females were still able to determine the sex of the egg. Overall, the two species appear to be in direct competition for resources.