This paper wasp has been stylopized by a species of
Stylopidae (Order Strepsiptera). The wingless females can be seen
protruding from between the wasp's abdominal segments. Male stylopids
are winged and mate with the embedded females through a narrow slit-like
opening situated between the female's head and thorax. Highly mobile
larvae are subsequently released from the same opening. The triangulin
larvae locate new hosts burrowing into them through the cuticle. Once
inside they moult into maggot-like larvae that then feed internally on
the new host. Pupation takes place inside the host with males emerging
to fly away, but females stay embedded with only their highly modified
head an thorax protruding (four individual females are evident in the
above photographs). Stylopid infestation is not fatal to the host wasp.
Bequaert J.C. 1918. A revision of the Vespidae of the Belgian Congo based on the collection of the American Museum Congo Expedition: with a list of Ethiopian diplopterous wasps. Bulletin American
Museum of Natural History 39: 1-384.