Asian mud-daub wasp (Sceliphron curvatum) nest cells. The Asian mud-daub wasp is now an invasive species in Europe, where it was first recorded in 1979, and the Americas, where it was first recorded in 2013. The female wasp builds a 3 centimetre amphorae-shaped nest of liquified mud for each egg. When it has dried she fills it with paralysed spiders for the grub to eat, lays a single egg and builds a cap of mud to close it. After pupation the young wasp escapes by cutting away the lid of the jar. The mud cells are often produced in groups and can often be found in buildings, on furniture and curtains.