Photo: Kevin Krebs, CC BY 4.0, via Wikimedia Commons
Kansas City Pest Identification
Sceliphron caementarium, Chalybion californicum (blue mud dauber)Mud Dauber Identification
The solitary wasp that builds mud tubes on your garage wall, porch ceiling, or under the deck. Long, thin, and unbothered by you — a nuisance for the mud, not a stinging threat.
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How to Identify It
Very narrow thread-like waist and long body. The black-and-yellow mud dauber is the common one; the blue mud dauber is metallic blue-black. Nests are organ-pipe or blob-shaped mud tubes, each cell packed with paralyzed spiders for the larva.
Size: 20–28 mm
Commonly Confused With
Paper wasps (thicker, hanging legs, paper comb) and yellowjackets. If it is walking on mud or carrying a spider, it is a mud dauber.
Why It Shows Up
Sheltered, dry surfaces to build on: garages, porch ceilings, under eaves, inside sheds and barns, behind shutters, and in attics through vents. They also enter through open garage doors.
Where Homeowners Find It
Garage and shed walls, porch ceilings, eaves, electrical boxes, grill lids, and the underside of decks and boat covers. Old nests with exit holes are empty.
Seasonal Activity in KC
May through September.
Risk Level
Almost none. They rarely sting people and do not defend the nest. They actually reduce spider populations, including black widows. The mud nests can stain siding and clog vents and equipment.
What You Can Do Yourself
- • Scrape off nests with a putty knife and wash the spot; they rebuild less on smooth, clean surfaces.
- • Keep garage doors closed and screen vents.
What Professional Treatment Involves
Nest removal and a residual on favored surfaces if they are a recurring problem. Most of the time we tell customers this one is not worth paying to treat.
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Common Questions
How do I tell a mud dauber from something that looks similar?
Paper wasps (thicker, hanging legs, paper comb) and yellowjackets. If it is walking on mud or carrying a spider, it is a mud dauber.
Do I need professional treatment for mud dauber?
Nest removal and a residual on favored surfaces if they are a recurring problem. Most of the time we tell customers this one is not worth paying to treat.