Mud Daubers

Family: 
Sphecidae and Crabronidae (two families of wasps) in the order Hymenoptera (ants, bees, wasps)
Description: 

Mud daubers are familiar wasps with narrow or threadlike waists. These solitary wasps belong to a number of related groups, but we call them “mud daubers” because they all build their nests out of mud. You can identify the different species by coloration and by the distinctive nest architecture.

The black-and-yellow mud dauber (Sceliphron caementarium) constructs nest cells side by side or on top of one another; the final product is rounded and about the size of a lemon or a fist.

The organ pipe mud dauber (Trypoxylon politum) is black with blue wings, with white “stockings” on the hind legs. It makes vertical, parallel rows of cells; the finished product looks like a pipe organ.

The blue mud dauber (Chalybion californicum) is a pretty metallic blue; it does not build nests but instead reuses those of one of the other species. Instead of mud, it carries water, which it uses to soften and remodel the mud of the older nests.

Size: 
Length: about 1/2 to 1 inch.
Habitat and conservation: 
Nests are often seen in barns, garages and the eaves of houses. Howard Ensign Evans wrote, "the passing of the outdoor privy was a sad day" for mud daubers! In nature, nests are built in cave entrances, under rock overhangs and in similar places. A female carries mud balls from a puddle to the nest site; a cell takes about an hour to construct. Their "singing" while applying mud to a nest is one of many interesting habits and behaviors you can enjoy.
Foods: 
Mud daubers place paralyzed spiders in the nest cells as provisions for their young. Stinging the spider only only subdues the spider but also helps preserve it, so when the wasp larvae hatch, they have fresh meat. Black-and-yellow mud daubers prefer crab spiders and other small, colorful species. Organ pipe mud daubers also provide spiders for their young. Blue mud daubers use large numbers of black widow spiders.
Distribution in Missouri: 
Statewide.
Status: 
Most people would agree that any natural remedy that reduces black widows around the home is a good thing. Because blue mud daubers (which specialize in hunting black widows) need the old nests of the other two species, consider allowing any mud daubers to build nests where you can tolerate them. Mud daubers reserve their sting only for prey and rarely sting humans (they do so only if handled roughly). They don't defend their nests like paper wasps and other social species.
Life cycle: 
All Missouri mud daubers pass the winter as immature individuals in the nests. The black-and-yellow mud dauber has two generations each summer. Male organ pipe mud daubers are among the few male hymenopterans (ants, bees, wasps) to stay at the nest: A male "stands guard" while a female is away collecting spiders, in order to protect against other insects that might sneak in and parasitize the nest. Mating occurs frequently on her visits to the nest.
Human connections: 
Mud dauber nests are occasionally considered unsightly nuisances on human buildings. However, before you eradicate your mud dauber nests, remember that these relatively harmless insects comb the environment for spiders, including black widows.
Ecosystem connections: 
Mud daubers prey on spiders, controlling their numbers. Numerous other insect species "prey" on mud daubers by parasitizing their nests, eating their eggs and larvae as well as the spiders intended as their food. Many birds, mammals, amphibians and reptiles all prey on wasps, as well.