Life History of Oxybelus variegatus Wesmael, 1852 (Hymenoptera: Crabronidae) with a Description of the Mature Larva

SIMPLE SUMMARY: Poor knowledge of the morphology of larvae and natural history data on the genus Oxybelus prompted us to research the rare digger wasp Oxybelus variegatus. We have described the mature larva for the first time and analysed the nesting behaviour of females, nest structure, prey range, phenology and accompanying kleptoparasites. Our findings indicate that this endangered species may inhabit strongly anthropogenic habitats and shows a potentially effective role in controlling dipteran crop pests such as Delia platura. ABSTRACT: The first comprehensive information on the bionomics of the digger wasp Oxybelus variegatus Wesmael, 1852 is presented. Females nested in small aggregations in crevices between paving stones of a frequently used pedestrian pathway in lowland agricultural wasteland. Nests were dug in the ground using mandibles, legs and abdomen. The nest consists of a main burrow with one or, rarely, two cells. The mature larva is described for the first time. The egg stage lasts for about two days before the larva hatches. The female provisioned each cell with an average of 11 paralysed male flies of Delia platura (Meigen, 1826) (Diptera: Anthomyiidae). Numerous females of dipteran kleptoparasites were observed in the nesting area of O. variegatus. However, only a few nests were infested by larvae of Senotainia conica (Fallen, 1810).