Sceliphrini

Sceliphrini, a tribe of thread-waisted wasps, are better known as mud daubers, dirt daubers, or mud wasps. Their name comes from the nests built by females, who shape mud with their mandibles. These wasps are long and slender, reaching about an inch in length. They are generally not aggressive, though they may become hostile if provoked, and stings are rare.

These wasps construct mud nests with cylindrical cells, often on cliffs or buildings. Each cell holds a single egg and is stocked with spiders. Black-and-yellow mud daubers in the genus *Sceliphron* build their own nests. Those in the subgenus *Sceliphron* (*Sceliphron*) create multi-cell nests encased in a second mud layer, while those in the subgenus *Sceliphron* (*Hensenia*) build single-cell nests. Blue mud daubers, in the genus *Chalybion*, reuse abandoned nests of other species. Mud daubers often return to the same sites year after year, producing many nests in protected spots, which then become nesting sites for other wasps, bees, and insects. The young spend the winter inside the nest.

As parasitoids, adult mud daubers hunt and paralyze prey for their larvae, packing up to a couple dozen small spiders into each cell. Black-and-yellow mud daubers target small, colorful spiders like crab spiders, orb weavers, and some jumping spiders. Blue mud daubers hunt cobweb spiders, including widow spiders, sometimes shaking the web to lure out the host. The wasp grabs and stings the spider, paralyzing it without killing it, so it can be carried and stored until the larva feeds. The wasp typically lays an egg on the prey and seals the cell with mud. Adults of both sexes often drink flower nectar.

Concentrating offspring in one place makes nests highly vulnerable to predators. Once discovered, a nest can be plundered cell by cell. Various parasitoid wasps, from tiny chalcidoids to bright green cuckoo wasps, attack mud dauber nests, stealing provisions and offspring as food for their own young.

Mud daubers have been linked to several aviation incidents. On September 12, 1980, Florida Commuter Airlines Flight 65 crashed, killing all 34 aboard. Before the flight, a mud dauber nest was found in a pitot tube and cleaned using an unapproved method; the NTSB listed improper cleaning as a possible factor. On February 6, 1996, Birgenair Flight 301 crashed into the Atlantic, killing all 189 on board.