I was fascinated by a wasp dragging a dead-looking spider larger than itself towards what looked like a nest at our home in Fish Hoek. Experts at I-Spot identified the wasp as a Spider Wasp (Pompilida) and the spider as a Velvet Spider. Unfortunately I was unable to wait to see the spider being drawn into the nest – it would have been a sight worth seeing!
Riaan Stals had made this comment on I-Spot:
“Please do not be disappointed that your spider wasp will not be identified beyond the level of family. The Pompilidae is a large family, of which the southern African representatives are poorly known. Moreover, there are different genera and species that look alike, and nobody presently on iSpot has the knowledge to tell them apart.”
The following info about Spider Wasps has been gleaned from http://en.wikipedia.org/wiki/Pompilidae:
There are in the region of 5 000 species of Spider Wasps in six subfamilies. All are solitary.
They typically have slender bodies with long spiny legs and most have long wings. Generally black in colour, they may have orange, red, yellow or while markings.
A spider wasp feeds on a single spider, which it paralyses with a toxic sting. After dragging the spider to its nest, the wasp lays a single egg on the spider’s abdomen, after which it closes the nest.
According to Wikipedia, the size of the host spider can influence the gender of the emergent wasp with larger spiders leading to the birth of female wasp. On hatching the wasp larva feeds on the spider, which is still alive, after which it spins a silk cacoon and pupates, emerging as an adult wasp the next summer.
Adult wasps feed on nectar
(Spacing has gone wonky!)
The following info about the Velvet Spider is from Filmer’s Spiders – an Identification Guide for Southern Africa by Martin R Filmer and revised by Norman Larsen.
(As the I-Spot experts could not definitely say what particular type of Velvet spider this one happens to be I will only describe those genera might be relevant.)
Velvet Spiders are “corpulent” spiders , bluntly rounded in front, with short thick legs. Males are usually smaller and different in colour from the females.
They may be:
sedentary and web-bound
free-running and ground- living
sedentary and ground -living
sedentary and plant-living
They are also diurnal or nocturnal.
Amongst the Velvet spiders described in Filmer’s that fit the bill for “my” spider are:
Horned Velvet spiders (Genus: Dresserus) which live in messy shroud-like webs under stones. These sacs hang when the stone is lifted. They are reluctant to leave their nests and have to be prized out. They are unaggressive and harmless.
Tree velvet spiders (Genus: Gandanameno) are found under loose bark, in crevices and old knots of trees. Well established communities of females create a maze of webs and tunnels.
Both the above are found throughout South Africa and are harmless.
Community Nest Spiders (Stegodyphus dumicola and Stegodyphus mimosarum) are greyish brown and usually with patterns on their abdomens. They build large untidy nests in bushes, plants and trees or between trees. A large number of males, females and juveniles live together in one nest which consists of tunnels, chambers and catch webs set out at various angles. Prey landing on these are killed by a group of spiders and shared with the whole community. These spiders are harmless and found throughout southern Africa.