A simple sand wasp
Published 21 October 2022
Meet Argogorytes. Sand wasps of this genus may be found around the world, being known from all continental regions except sub-Saharan Africa (Bohart & Menke 1976). Over 25 species have been described to date though the genus is poorly revised in many places.
Argogorytes is a morphogically generalised genus that has been widely considered one of the most primitive of its family. Distinguishing features include eyes with a sinuate inner margin, placed so the frons is narrower at the level of the mid ocellus than just below it, a strong acetabular carina on the underside of the mesopleuron, and a foveate sulcus at the front of the scutellum. Antennae are not modified in the males, and the gaster is not strongly pedunculate. Males have the eighth sternite on the gaster apically narrow and sword-shaped. Females have a distinct pygidial plate with dense, fine bristles towards the apex (Bohart & Menke 1976). Species of the genus remain structurally quire similar throughout its range.
Knowledge of the natural history of Argogorytes is limited but was reviewed by Callan (1980). Females nest in small colonies, digging holes in sandy soil or slopes. Burrows contain multiple cells and may be up to twenty centimetres long and ten centimetres deep. Recorded prey are planthoppers of the Issidae or spittlebug nymphs of the Aphrophoridae. The latter are plucked by the wasp from their protective mass of spittle, either by plunging the head in or by inserting the legs and sting. The prey is then flown back to the nest carried underneath the wasp between the mid legs. Nests are often left open when the female is away but at least one species, the East Asian A. mystaceus grandis, has been reported to close them while foraging. Each cell of a nest may contain multiple prey individuals (up to 30 have been recorded in a unicellular nest of the Palaearctic A. fargeii) but it does not seem to have been established whether multiple eggs may also be laid in a cell, or whether a single egg is laid and the larva consumes multiple prey.
Adult Argogorytes have been observed feeding at flowers of Umbelliferae. Males are rarely reported but one aspect of male biology that has received its fair share of attention is the relationship between the Palaearctic A. mystaceus and the orchid Ophrys insectifera. The latter species, one of the notorious bee orchids, produces pheromones resembling those of a sexually receptive Argogorytes female. And the males just can’t help themselves.
References
Bohart, R. M., & A. S. Menke. 1976. Sphecid Wasps of the World. University of California Press: Berkeley.
Callan, E. M. 1980. Nesting behavior and prey of Argogorytes Ashmead (Hymenoptera: Sphecidae). Journal of the Washington Academy of Sciences 70 (4): 160–165.