Solitary Anthophorid bees

By Geoff Tribe (Images by Jenny Cullinan and Karin Sternberg)

Anthophorid 1

There are over 100 species of bees in southern Africa belonging to the family Anthophoridae which has a world-wide distribution. Anthophorid bees generally resemble the basic stout form of small carpenter bees but with abdomens that are usually striped in shades of black and grey. The flight of these hairy bees is fast and erratic and accompanied by a shrill hum. All African species nest in the soil, usually in sandy banks where they construct a deep central burrow from which leads short side burrows that end in cell chambers in which their brood is reared. The female bee provisions the brood cells which are lined with a wax-like material with a mixture of nectar and pollen, onto which she lays an egg. Some species construct an entrance made of soil particles cemented together with saliva which projects from the soil.
Males of many anthophorid species have antennae that are unusually long and thus anthophorids may also be known as ‘long-horned bees’. One species found in the Cape Peninsula closely resembles the dark Cape bee (Apis mellifera capensis) except for its longer antennae and slightly smaller size. digger bee 3Males of anthophorids may form ‘sleeping clusters’ where they congregate by attaching themselves to a twig within a bush by means of their large mandibles. One such cluster consisting of 68 males of the same species was located one evening after the sun had set in the Natal Drakensberg near Cathedral Peak forestry station in about 1986.
A large number of anthophorids are known as ‘cuckoo bees’ but their behaviour is not that of true parasites. This cleptoparasitism is widespread in the Anthophoridae and related families where the female enters a brood cell already provisioned by a host female and lays an egg of her own. The ‘cuckoo’ females lay an egg on the accumulated larval provisions of other bee species instead of provisioning their own nests. The egg or young larva of the host bee is either killed directly by the female cuckoo or killed by the ‘cuckoo’ larva. One such ‘cuckoo’ species found commonly in the south-western Cape is Thyreus delumbatus which ‘parasitizes’ Anthophora and Amegilla bees where they enter their nests to deposit their eggs. This ‘cuckoo’ bee is slightly smaller than a honeybee and has a ‘fish-bone’ pattern in black on its otherwise powder-blue body.
There are also cuckoo wasps such as the bright metallic green Stilbum cyanurum which lay eggs in nests of solitary wasps and bees, their larvae also feeding on the host’s provisions or larvae. These cuckoo wasps are extremely hard and strongly sculptured to withstand attack by the hosts, and are able to roll up into a ball in self-defence.

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