Polistes atrimandibularis

P. atrimandibularis is the smallest of the social Polistes parasites. The size of the host's species brood cells determines P. atrimandibularis size, with the smaller P. atrimandibularis emerging from the nests of P. gallicus and P. associus. Likewise, the larger P. atrimandibularis emerge from the nests of P. dominula instead. This paper wasp has enlarged mandibles, used as weapons to injure hosts that resist parasite intrusion. They also have an enlarged first femur and a longer posterior tibia that is useful for when they must maintain a dominant position within the host colony.

P. atrimandibularis is rare in Europe, found mainly around the Mediterranean and Caspian basin, but it ranges from south and south-central Europe to western Asia. They typically position themselves at higher elevations, although it is not unheard of to find colonies at lower elevations. Accordingly, one of the species that P. atrimandibularis parasitizes, P. biglumis, lives mainly in montane climates in Southern Europe. They do not possess the ability to build their own nests, so they must parasitize other wasps’ colonies.