Wikipedia
Agelaia is a genus of Neotropical social wasps (family Vespidae), with species from Mexico to northern Argentina. Fifteen of the 31 described species are found in Brazil. These species are swarm founders that nest in cavities. The nest generally is without an envelope.
The genus includes the species A. vicina that sometimes nests in attics in São Paulo, Brazil, and requires the services of the fire department for removal of the colony that can number more than 1,000,000 stinging wasps. It also includes A. pallipes that is a ground-nesting species found in South America and is considered one of the most aggressive wasps in the region.
These wasps are considered aggressive compared to other wasp species, and inflict a painful sting. The main component of the venom is Agelotoxin, a Phospholipase A2 direct haemolysin, which may cause a severe reaction in some patients.