These brightly colored wasps are master builders. They make nests of mud in shady sheltered places like bridges, garages, barns, and behind shutters. Their Latin name means builder of walls! They place captured spiders in the nests for their larvae to eat. You will often see the adults gathering pollen on flowers in late summer. They especially seem to like yarrow and Queen Anne’s lace. This species is native to the US and Canada but it was accidentally introduced to Europe and Australia.