Synoeca wasps are found from Mexico to Argentina. The genus is made up of five described species(Andena et al., 2009).
Synoeca surinama and S. septentrionalis are closely related and can be difficult to distinguish. S. septentrionalis has erect hairs on the first metasomal sternum and tergum; also, there is a dark triangular area on the sternum. The nests, too, are similar, but that of S. septentrionalis has a dorsally central groove, while that of S. surinama has a dorso-central keel.
S. septentrionalis ranges from Mexico south to Brazil, Peru, and Bolivia. These wasps aggressively defend the nest, and stings of all the Synoeca species are reported to be very painful to humans.
Photo location: Naranjo, Alajuela province, Costa Rica.
A similar Synoeca sp. wasp from French Guiana is also on this site.
American Insects site