The females usually build their nests in hollow or marrowy stems or branches. Some species also use abandoned feeding tunnels in the wood or build their nests in
plant galls. If there is a lack of space, the cells lie in lines one behind the other, otherwise they are branched. Short side passages are often first filled with bore dust and only later developed into cells. Each cell is supplied with 10 to 60
Aphididae, whereby the selection of the species is unspecific. The prey is either stunned with a sting or killed with the mandibles. Then they are grabbed with the mandibles and transported to the nest. When a cell is completely supplied, an egg is laid on the ground or in the middle of the cell between the prey animals. In many species, the larvae do not pupate in a complete
cocoon, but in a cap over the head, which can be a thin membrane that merges into the wall of the brood cell. Some species such as
Pemphredon lethifer also produce a fine second membrane just below the cap. From the inner cells of the nest usually hatch females, from the outer males. The genus is
proterandric, which means that the males hatch a few days before the females. In Central Europe, one generation per year is developed, in favourable years it can be two. The
imagines of many species feed on
honeydew, but sometimes also on the aphids themselves.
Parasitoids of the genus are reported to be from the
cuckoo wasps,
ichneumon flies,
Gasteruptiidae and
chalcidoid wasps. == Species (Europe) ==