Mud Daubers
(Sceliphron caementarium)
Solitary wasps that build distinctive tube-shaped mud nests on walls and under overhangs.
Overview
Mud daubers are solitary wasps that are extremely common around Bowling Green homes. They build distinctive tube-shaped or organ-pipe-shaped nests from mud, which are often found on exterior walls, under eaves, in garages, and inside sheds. Unlike social wasps, mud daubers are not aggressive and rarely sting — they do not have a colony to defend. They are actually beneficial because they prey heavily on spiders, including brown recluses and black widows.
Appearance
Mud daubers are slender wasps, 3/4 to 1 inch long, with a very distinctive extremely narrow, thread-like waist (petiole) connecting the thorax to the abdomen. Common species include the black and yellow mud dauber (black with yellow markings), the blue mud dauber (metallic blue-black), and the organ pipe mud dauber (solid black). Their body shape immediately distinguishes them from other wasps.
Habitat
Mud daubers build their nests on vertical surfaces that are sheltered from rain. Common locations include under eaves, on porch ceilings, inside garages, in attics, on the sides of buildings, and even on vehicles and equipment that are not frequently used. Nests are made of mud and may be tube-shaped, urn-shaped, or in a series of parallel tubes (organ pipe dauber).
Diet
Adult mud daubers drink nectar from flowers. However, they are specialist spider hunters — females capture and paralyze spiders, then carry them back to their mud cells as food for their larvae. A single mud cell may contain 20 to 30 paralyzed spiders. Different species target different spider types, including brown recluses and black widows.
Lifecycle
Females build individual mud cells, stock each cell with paralyzed spiders, lay a single egg in each cell, and then seal it. The larva hatches, feeds on the stored spiders, pupates within the cell, and emerges as an adult. The entire cycle takes about one generation per year. Adults are most active in spring and summer.
Signs of Infestation
- !Tube-shaped or organ-pipe-shaped mud structures on walls, under eaves, or inside garages
- !Solitary wasps carrying mud or spiders to a nest site
- !Old, broken-open mud nests with empty cells (where adults have emerged)
- !Dried mud deposits on walls and ceilings in garages and sheds
Prevention Tips
- ✓Scrape off mud nests regularly to discourage rebuilding in the same area
- ✓Seal gaps in garage doors, attic vents, and soffit openings
- ✓Paint or seal bare wood and masonry surfaces — smooth surfaces are less attractive for nest attachment
- ✓Reduce spider populations around the home (which reduces the food source for mud daubers)
Professional Treatment
Mud daubers rarely require aggressive treatment due to their low aggression and beneficial spider-hunting behavior. Old nests can simply be scraped off surfaces. Perimeter treatments can discourage nesting. For homes with excessive mud dauber activity, reducing the spider population around the home — their primary food source — is the most effective long-term strategy.
Did You Know?
- •Blue mud daubers specialize in hunting black widow spiders.
- •They do not reuse old nests — each female builds fresh cells.
- •A single mud cell may contain 20 to 30 paralyzed spiders stored as food for the larva.
- •Mud dauber nests have caused aviation incidents by clogging pitot tubes on aircraft.
3/4 to 1 inch
Black, metallic blue, or black and yellow
6
Very long, thin waist (petiole)
Dirt dauber, Mud wasp
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Other Stinging Insects in Our Library
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Carpenter Bees
Large, bumblebee-like bees that bore perfectly round holes into wood decks, fascia, and eaves.