A previously unreported association between a social wasp and a social passerine bird

An unreported association between the primitive social wasp Belonogaster lateritia Gerstaecker 1857 (Hymenoptera Vespidae) and the social bird Philetarius socius (Latham 1790) (Aves Ploceidae) is recorded. This association was observed only on active bird nests in a savannah area of central Namibia. On 25 checked nests, it was recorded on 5 of 5 active nests and 0 of 7 abandoned nests in savannah vegetation, never in desert areas. The wasp uses the inferior side of the bird nest aggregation, where tunnels open, as a substrate to fix the nest peduncle. The social and complex nests of P. socius are interpreted as an adaptive behaviour to reduce predation, and the presence of an aggressive associate wasp increases the defence against predators. The advantage for the wasp, besides the use of the substrate, could be the easiness of predation on flies attracted under the nest by the store of bird faeces.