Polybia sericea

Polybia sericea is a social, tropical wasp of the family Vespidae that can be found in South America. It founds its colonies by swarming migrations, and feeds on nectar as well as other arthropods. P. sericea is medium in size, and has a dark-colored body. The wasps build multi-tiered nests, and colony size can vary greatly between a few workers to a few thousand. Queens can be distinguished from workers by their greater body size and smaller head size. They tend to be polygynous, meaning that there are several egg-laying queens within a nest, with the result that workers are generally less related to each other than in other eusocial species. Workers are responsible for hunting and foraging, while queens are responsible for laying eggs, and have the most developed ovaries. When hunting for prey, workers rely heavily on visual and olfactory cues. Prey include arthropods such as green and brown caterpillars. Polybia sericea is a species within the genus Polybia of subfamily Polistinae. Polybia is the most diversified genus within tribe Epiponini, which is characterized by colony founding via swarming. Placement of Polybia among related genera has fluctuated, and the genus may be paraphyletic. P. sericea individuals are medium-sized wasps, about 17 mm long. They are dark in color, and tend to be slow-flying and docile, unless they are disturbed. Queens typically have larger abdomens, and smaller heads and wings than workers. Workers build enclosed, multi-tiered roughly spherical nests of carton paper maché-like pulp of plant fibres chewed with saliva. Nests are reddish-brown in color, and are not very large. They are typically built between two and five meters off the ground, in the branches of trees or shrubs. Individuals of P. sericea live in South America, and are commonly found throughout Brazil. A large presence of Polybia sericea inhabits the lower tropical Amazon region of Brazil. They tend to live in semi-arid climates, in open areas, around forest edges, and near rivers. This species prefers to live in areas with grasses, trees, and shrubs. This is likely because these areas make good places to build nests and to forage for food. P. sericea colonies can range from a few individuals, to a few thousand, but are typically made up of several hundred workers. The number of queens in a nest can range from one to several queens. New colonies are founded by swarming emigration, where the entire colony travels to a new nest site. This may happen when a nest becomes unsuitable for living or when a predator attacks the nest and forces the colony to leave. Swarm emigration occurs when a colony moves from the location of one nest to a new nesting site. This may occur for several reasons. One is if the colony sends a reproductive swarm from the original nest. This may happen if the colony has grown too big, and must split into two new colonies. In this situation, part of the colony will remain in the original nest, with a subgroup leaving to colonize a new nesting site. Other reasons swarm emigration occurs is if an old nest becomes unsuitable, or if the nest is attacked by a predator. At first, when the colony is driven from the nest, individuals assemble in groups of 2 or 3 around the original nest. Wasps will exchange between groups until the entire colony is assembled in one cluster. The colony may remain in this cluster for up to 2 days before migrating to the new site. Once the colony begins to travel, leading individuals will drag their gaster over prominent objects such as branches or tall grass. This releases a pheromone that other workers can follow to the new nesting site.