Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada

Species Sceliphron caementarium - Yellow-legged Mud-dauber Wasp

Black and Yellow Mud Dauber with a yellow waste - Sceliphron caementarium Wasp? - Sceliphron caementarium Wasp - Sceliphron caementarium Sexing a Black & Yellow Mud Dauber Wasp - Sceliphron caementarium - female sphecid - Sceliphron caementarium Black and Yellow Mud Dauber - Sceliphron caementarium Thread-waisted Wasp From Oregon - Sceliphron caementarium Sceliphron caementarium - Male behavior - Sceliphron caementarium - male
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon (Aculeata - Ants, Bees and Stinging Wasps)
No Taxon (Apoid Wasps (Apoidea)- traditional Sphecidae)
Family Sphecidae (Thread-waisted Wasps)
Subfamily Sceliphrinae
Tribe Sceliphrini (Mud-dauber Wasps)
Genus Sceliphron (Black Mud-dauber Wasps)
Species caementarium (Yellow-legged Mud-dauber Wasp)
Other Common Names
Black-and-yellow Mud-dauber (note: this name also applies to almost every species in the genus so is a very poor name for a particular species)
Black-waisted Mud-dauber (note: often used outside of the Americas where this is a unique trait; this trait is useless in the Americas where most of our species have black petioles and where the desert southwest population of S. caementarium often has a yellow petiole)
Explanation of Names
Sceliphron caementarium (Drury 1773)
caementarium = from the Latin caementārium ('mason, builder of walls')
Size
24-28 mm
Identification
Black body with variable amount of yellow markings. Pedicel (waist) about twice as long as the rest of the abdomen. In all cases, the hind legs are marked with copious yellow on the tibiae and tarsi.
Tips on how to determine sex:
Range
Throughout NA (s. Can. to C. Amer. and W. Indies) - Map (1)(2); accidentally introduced into Europe several times, well established in several countries since the 1970s(3)
Habitat
Adults nectar at flowers; mud nests are built in all kinds of sheltered locations, incl. man-made structures, rock ledges, etc. Adults collect mud for nests at puddle/pool edges.(4)(5)
Season
mostly: Apr-Oct (2)
Food
Nests are provisioned with spiders; adults common at flowers(4), especially parsnip and water parsnip, and visit hummingbird feeders.(5)
Remarks
Nests may comprise up to 25 cylindrical cells, with typically 6-15 (up to 40) prey spiders per cell. The female may provide the cells with a temporary closure (a thin mud curtain) to keep out parasites while she is collecting prey. Once the cell is stocked, she lays an egg on one of the last prey and seals the cell with a thick mud plug. She may then add more mud to cover the entire cluster of cells.(5)
Adults are common where water splashes on bare soil (MAQ, pers. obs., 2019).

Though the species is globally known for its black petiole, a population in the western US (OR, CA, NV, UT, AZ, CO) has a yellow petiole.
See Also
In Texas, from the Rio Grande Valley north to about San Antonio, S. assimile co-occurs. S. assimile is noted for its entirely black, to nearly-so, hind legs.