Are mud daubers dangerous to kids or pets?

No — mud daubers are solitary wasps with no colony to defend, and they essentially never sting people or animals. University of Minnesota Extension states explicitly: 'Not aggressive, stings are rare.' Because there is no shared nest to protect, there is no defensive swarming behavior. A mud dauber flying around your wall or porch is building or checking her solitary mud nest, not sizing you up. Stings from mud daubers are so rare that they are considered a non-event by extension entomologists — and unlike a social-wasp sting, there is no alarm pheromone to recruit additional wasps. Your children and pets are safe.

Are mud daubers in New Hampshire?

Yes — the black-and-yellow mud dauber (Sceliphron caementarium) is a common, high-prevalence resident across southern and central New Hampshire. You will find its gritty mud-cell clusters on barns, garages, house siding, under bridge overhangs, and on any sheltered wall across Manchester, Nashua, Concord, Derry, Bedford, and the surrounding Rockingham, Hillsborough, Merrimack, and Strafford county area. The organ-pipe mud dauber (Trypoxylon politum) is a separate species sometimes listed for the Northeast, but BugGuide contributed-data shows zero New Hampshire records for it. Organ-pipe mud daubers are sparse to likely absent here — the black-and-yellow species is what New Hampshire homeowners see.

Should I kill a mud dauber?

No — mud daubers are beneficial solitary wasps and there is almost never a reason to kill them. They hunt spiders — including black widows where those occur — providing free spider control. If the mud nest bothers you cosmetically, simply scrape it off the wall; the wasp will not defend it. University of Minnesota Extension states: 'Does not harm buildings where they build their nests,' so even structural concerns are unfounded. The single sensible action if mud nests accumulate near a door or on painted siding is physical removal plus sealing the surface so it is less attractive next season. No insecticide is needed or recommended.

What are mud daubers good for?

Mud daubers are specialist spider predators — they paralyze spiders and stock their mud cells with them as food for their larvae. A single black-and-yellow mud dauber female provisions each cell with multiple spiders. Wikipedia documents that black widow spiders, where present, are among the species mud daubers prey upon, giving them an outsized beneficial role in areas where those spiders occur. Beyond spider control, mud daubers are minor pollinators as adults, foraging nectar alongside their hunting. The bottom line is that a mud dauber on your property is doing you a favor: it is reducing the local spider population and requiring nothing in return.

Do mud daubers damage my house?

No. University of Minnesota Extension is explicit: 'Does not harm buildings where they build their nests.' Mud daubers do not chew wood, tunnel into siding, or compromise structural materials. Their mud nests are superficial — attached to the exterior surface of walls, beams, or eaves. The only realistic concerns are cosmetic: dried mud residue on painted siding or staining from moisture trapped under a large mud mass. Both are easily addressed by scraping the nest off with a putty knife when the wasp has vacated. No chemical treatment is needed.

How do I tell a mud dauber from a yellowjacket?

The differences are clear once you know what to look for. Mud daubers have a dramatically elongated, thread-like waist (petiole) connecting the thorax and abdomen — a 'thread waist' that is unique and obvious. Yellowjackets are compact and chunky with no visible waist constriction. Mud daubers build their nests from mud — rough, gritty, brownish-gray tubes or clusters on walls and eaves. Yellowjackets build paper nests (chewed wood pulp) that are either enclosed in a gray football-shaped envelope, hidden underground in a soil burrow, or stuffed into a wall void. Mud daubers are docile and will fly past you without interest; yellowjackets are defensive and will sting repeatedly when their nest is disturbed. If you see mud tubes on your wall, it is a mud dauber — harmless. If you see a papery nest or wasps flying in and out of a hole in the ground or wall, it is a social wasp — worth a professional evaluation.

What is the mud tube on my wall, shed, or barn?

Almost certainly the nest of a black-and-yellow mud dauber (Sceliphron caementarium). Females collect wet mud, carry it in their mouthparts to a sheltered vertical surface, and shape it into oval cells. Each cell gets packed with paralyzed spiders, receives one egg, and is sealed over. The finished result looks like a rough cluster of oval mud blobs, sometimes in long parallel rows, on a wall, barn beam, under an eave overhang, or on masonry. The nest is abandoned as soon as it is sealed — the wasp moves on to build the next cell or has completed her season. You can safely scrape the nest off at any time; there is no live wasp inside defending it after it is sealed.

What is the difference between a mud dauber and an organ-pipe mud dauber?

Both are solitary mud-building wasps in the same behavioral category — docile, spider-hunting, never aggressive — but they are different species with distinct nests. The black-and-yellow mud dauber (Sceliphron caementarium) builds clustered oval mud cells, often in an irregular mass. The organ-pipe mud dauber (Trypoxylon politum) builds its cells in long parallel tubes that resemble pipe-organ pipes — a striking architectural difference. In New Hampshire, this distinction is largely academic: BugGuide contributed-data shows zero NH records for the organ-pipe species. The organ-pipe mud dauber has a distribution centered in the southern and mid-Atlantic US and is sparse to likely absent in New Hampshire. The mud nest you see in NH is the black-and-yellow species.

Will another wasp move into an abandoned mud nest?

Sometimes — old mud dauber cells can be reused or taken over by other cavity-nesting species, including other solitary bees and wasps. This is actually a sign of a healthy local insect community rather than a problem. If you prefer not to host any subsequent residents, scraping the nest off when it is clearly abandoned (no wasp activity around it) is all you need to do. You can then seal the surface with paint or caulk to make it less attractive for future nesting. Neither the original mud dauber nor any subsequent occupant poses a sting risk to people — cavity-nesting solitary insects are uniformly docile.

Should I remove the mud nest?

Only if you want to — there is no safety reason to remove an abandoned mud dauber nest. The wasp is gone, there is no colony, and there is no sting risk. If the nest is on painted siding and you are concerned about staining, or it is in a spot where it looks unsightly, scraping it off with a plastic putty knife is the entire job. Do it any time — spring, summer, or fall. No protective gear is needed. If you want to reduce future nesting in the same spot, seal or paint the surface; mud daubers prefer rough, porous surfaces for adhesion. What you should not do is apply pesticide to a mud dauber nest — it is unnecessary, the wasp is probably not even present, and it will not prevent future nesting by other species the way a physical seal will.

Daniel Brady · NH-Licensed Pesticide Applicator · License #782664

|Reviewed by Daniel Brady

Mud Daubers in New Hampshire — ID, Mud Nests & Sting Risk

Identification

Mud daubers are slender, thread-waisted solitary wasps that build distinctive mud tube nests on sheltered walls, eaves, sheds, and barns across New Hampshire. The black-and-yellow mud dauber (Sceliphron caementarium) is the species NH homeowners actually see — it is common statewide, hunts spiders (including black widows), and essentially never stings. University of Minnesota Extension states plainly: 'Not aggressive, stings are rare. Does not harm buildings where they build their nests.' If you have a mud nest, you can simply scrape it off — no chemical treatment is needed.

Quick facts

Size: 24–28 mmBlack-and-yellow mud dauber (Sceliphron caementarium); only US Sceliphron with yellow-marked legs; Wikipedia / en.wikipedia.org
Sociality: Solitary — no colony, no nest defenseEach female builds and provisions her own mud cells; UMN Extension
Sting: Essentially never stingsUMN Extension verbatim: 'Not aggressive, stings are rare' — no defensive behavior around nest
Prey: Paralyzed spiders, including black widows where presentWikipedia / Sceliphron caementarium; UMN Extension

Size
24–28 mm
Black-and-yellow mud dauber (Sceliphron caementarium); only US Sceliphron with yellow-marked legs; Wikipedia / en.wikipedia.org
Sociality
Solitary — no colony, no nest defense
Each female builds and provisions her own mud cells; UMN Extension
Sting
Essentially never stings
UMN Extension verbatim: 'Not aggressive, stings are rare' — no defensive behavior around nest
Prey
Paralyzed spiders, including black widows where present
Wikipedia / Sceliphron caementarium; UMN Extension

Overview

The wasp that hunts black widows — and almost never bothers people

If you've found a cluster of rough, gritty mud cells plastered on your garage wall, shed siding, barn beam, or eave overhang, you are looking at the work of a mud dauber — almost certainly the black-and-yellow mud dauber (Sceliphron caementarium), the most common solitary wasp in southern and central New Hampshire. The good news, and the thing most pest-control pages bury: this wasp is among the most harmless insects you will ever find on your property.

Mud daubers are solitary. That single word changes everything. Unlike paper wasps or yellowjackets, there is no colony here, no queen to protect, no workers to mobilize in defense. Each female builds her own mud nest alone, stocks it with paralyzed spiders as food for her larvae, seals it, and flies away. University of Minnesota Extension puts it plainly: 'Not aggressive, stings are rare. Does not harm buildings where they build their nests.' The wasp is gone. The nest is an empty clay container. You can scrape it off the wall at any time, with no protective gear, and nothing bad will happen.

The black-and-yellow mud dauber earns a second look for another reason: it hunts spiders, including black widows in regions where they occur, making it a genuine beneficial predator. That distinctive thread-waisted silhouette — long petiole connecting thorax to abdomen, yellow legs, tawny wings — is a signal that you have a spider-control specialist on your property, not a threat.

New Hampshire also has a second mud dauber species, the organ-pipe mud dauber (Trypoxylon politum), but BugGuide contributed-data shows zero NH records for this species; it is at the northern edge of its range and sparse to absent here. The black-and-yellow mud dauber is the one NH homeowners see. This page covers how to identify both, how to read a mud nest, and when — if ever — you need to do anything about it.

New Hampshire context

Mud daubers in southern and central New Hampshire

The black-and-yellow mud dauber is a well-established, HIGH-prevalence resident across southern and central New Hampshire. You will find its mud-cell clusters on barn siding in Milford and Bristol, on garage walls in Manchester and Nashua, under bridge overhangs in Concord, on cedar siding in Bedford and Derry, and on practically any sheltered south-facing wall across Rockingham, Hillsborough, Merrimack, and Strafford counties. UNH Cooperative Extension notes solitary mud daubers as a common part of the NH stinging-insect picture — and one that almost never poses a sting risk. Mud daubers are active all summer. Females build and provision mud cells from late spring through late summer, provisioning each cell with multiple paralyzed spiders before sealing it and moving on. Unlike the social paper wasps and yellowjackets whose colonies collapse at hard frost, individual mud daubers simply complete their season's provisioning and the next generation overwinters as pupae inside sealed mud cells. The organ-pipe mud dauber (Trypoxylon politum) is occasionally listed for the northeastern US, but BugGuide contributed-data shows zero New Hampshire records for this species, compared to one in Massachusetts, one in Rhode Island, and six in New York. We report this honestly: organ-pipe mud daubers are sparse to likely absent in New Hampshire. What you see on your NH wall is the black-and-yellow species.

Species present in NH

Black-and-yellow mud dauber (Sceliphron caementarium)
Organ-pipe mud dauber (Trypoxylon politum) — sparse/likely absent in NH

Peak activity · Late spring through late summer (provisioning active June–August)

We serve these communities

ManchesterNashuaConcordDerryBedfordSalemHudsonAmherstAuburnGoffstownHooksettLitchfieldLoudonMilfordBristol

First-frost anchor: Manchester first hard frost ~Oct 19 (50%) / Oct 29 (80%) per NOAA 1991–2020 normals — mud dauber adults are done provisioning well before frost

UNH Cooperative Extension includes mud daubers in its NH stinging-insect guidance (Resource000532) and frames solitary wasps as non-aggressive species that almost never sting unless directly handled.

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Service Area Map

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Field identification

How to identify mud daubers — and tell their mud nests from paper wasp nests

The mud dauber's body tells you immediately that you are dealing with a solitary species — built nothing like the stocky, defensive yellowjacket. Three field marks separate it from every other common NH wasp.

Black-and-yellow mud dauber

Also called: Mud wasp, Dirt dauber

Found in New HampshireSolitaryLow aggression

Scientific name: Sceliphron caementarium
Family: Sphecidae
Sociality: Solitary
Size: 24–28 mm
Coloration: Black thread-waisted body with yellow legs (the only US Sceliphron with yellow-marked legs) and yellow thorax markings; long petiole (approximately half the abdomen length) creating the signature 'thread waist'; tawny/amber wings; overall slender silhouette
Range: Common throughout New Hampshire — HIGH statewide prevalence; native to eastern North America; the mud dauber NH homeowners see
Nest style: Clustered oval mud cells plastered to sheltered vertical surfaces — walls, barn beams, eaves, under bridge overhangs, masonry. Rough, gritty texture. Each sealed cell contains paralyzed spiders and one egg
Beneficial role: Major spider predator, including black widows where present; minor pollinator as an adult

Sting risk

Essentially never — UMN: 'stings are rare'

Nest defense

None — solitary, no colony to protect

Season

Active all summer provisioning mud cells (June–August peak)

Waist (petiole)

The defining feature: an extremely elongated, thread-like connection between the thorax and abdomen — often as long as half the abdomen itself. This 'thread waist' is far more pronounced than on any social wasp and is visible from several feet away. A chunky waist = social wasp; a thread waist = solitary mud dauber or digger wasp.

Legs

Bright yellow — the single fastest color cue. Sceliphron caementarium is the only US Sceliphron species with yellow-marked legs. Combined with the thread waist, yellow legs confirm identification instantly.

Body (overall)

Black with yellow thorax markings; smooth, non-hairy surface. Overall impression is very slender and elongated compared to paper wasps or yellowjackets. Wings are tawny/amber and translucent, held flat at rest.

Abdomen

Elongated and tapered, attached to the petiole at the narrow thread. The abdomen and petiole together make up most of the wasp's length. No envelope or papery comb — the nest is entirely separate, made of mud on a nearby surface.

Common look-alikes

Eastern yellowjacket (Vespula maculifrons)
How to tell: Yellowjackets are compact and chunky with no visible waist constriction — the opposite of a mud dauber's thread waist. Yellowjacket nests are paper (chewed wood pulp) — either a gray enclosed envelope nest, an underground burrow colony, or a hidden wall-void nest. Mud dauber nests are mud — rough, gritty tubes or clusters on a wall or beam. Yellowjackets are aggressively defensive; mud daubers will fly past you without interest. The nest material alone (mud vs. paper) is definitive.
Blue mud dauber (Chalybion californicum)
How to tell: The blue mud dauber is a close relative with a metallic steel-blue or blue-black body instead of the black-and-yellow coloration of Sceliphron. It often reuses and renovates Sceliphron mud nests rather than building new ones, so if you see a metallic-blue thread-waisted wasp at an existing mud nest, it may be Chalybion. Both are equally harmless and docile — the distinction is primarily academic for NH homeowners.
Organ-pipe mud dauber (Trypoxylon politum)
How to tell: Shiny black overall (no yellow markings) with pale hind-leg tips and metallic-blue wings. Its nests are long parallel tubes arranged like pipe-organ pipes rather than the clustered oval cells of Sceliphron. In New Hampshire, Trypoxylon is sparse to likely absent (0 BugGuide NH records). If the mud nest you see consists of parallel tubes rather than clusters, it may be Trypoxylon — but it is equally harmless either way.

Two mud dauber species: which one is in New Hampshire?

Prevalence based on UNH Cooperative Extension survey data.

Species	Size	NH status	Prevalence	Typical nest
Black-and-yellow mud dauber Sceliphron caementarium	24–28 mm	Native	HIGH	Clustered oval mud cells on sheltered walls, eaves, barn beams — rough gritty texture
Organ-pipe mud dauber Trypoxylon politum	13–25 mm	Native	LOW	Parallel mud tubes resembling pipe-organ pipes on vertical surfaces

Species

Size

NH status

Prevalence

Typical nest

Black-and-yellow mud dauber

Sceliphron caementarium

24–28 mm

Native

HIGH

Clustered oval mud cells on sheltered walls, eaves, barn beams — rough gritty texture

Organ-pipe mud dauber

Trypoxylon politum

13–25 mm

Native

LOW

Parallel mud tubes resembling pipe-organ pipes on vertical surfaces

Common Questions

Frequently asked

References

Sources & further reading (8)

[1]
University of Minnesota Extension — Mud Daubers
extension · Verbatim: 'Not aggressive, stings are rare. Does not harm buildings where they build their nests.' Mud dauber docility and identification · verified Jun 2026
[2]
University of Maryland Extension — Mud Daubers
extension · Mud dauber docility ('not aggressive'), ID cues, solitary lifestyle, no nest defense · verified Jun 2026
[3]
Wikipedia — Sceliphron caementarium (Black-and-yellow mud dauber)
encyclopedia · Size 24–28 mm; only US Sceliphron with yellow-marked legs; spider provisioning including black widows; native range · verified Jun 2026
[4]
Wikipedia — Organ pipe mud dauber (Trypoxylon politum)
encyclopedia · Organ-pipe nest description (parallel tubes); range (southeastern Canada to eastern US); male guards nest while female hunts · verified Jun 2026
[5]
BugGuide — Trypoxylon politum (Organ-pipe mud dauber) occurrence data
encyclopedia · NH data-gap confirmation: 0 New Hampshire records vs MA 1, RI 1, NY 6 — organ-pipe mud dauber sparse/likely absent in NH · verified Jun 2026
[6]
UNH Cooperative Extension — Controlling Wasps, Bees and Hornets Around Your Home
extension · NH solitary-wasp context; mud daubers as non-aggressive component of NH stinging-insect picture; after-dark treatment guidance for social wasps · verified Jun 2026
[7]
Northern New England Poison Center
medical · 24/7 poison control for NH/ME/VT; 1-800-222-1222; anaphylaxis guidance · verified Jun 2026
[8]
NOAA / The Old Farmer's Almanac — NH Frost Dates (Manchester, 1991–2020 normals)
gov · Manchester first hard frost ~Oct 19 (50%) / Oct 29 (80%); NOAA 1991–2020 normals · verified Jun 2026

Written & reviewed by

Verified

Daniel Brady

NH-Licensed Pesticide Applicator · License #782664 (NHDAMF, RSA 430)

Daniel Brady is the New Hampshire–licensed applicator behind Anchor Pest Services, a family-owned pest control company serving the Manchester area since 2017.

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Last updated Jun 2026

Anchor Pest Services

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Mud Daubers in New Hampshire — ID, Mud Nests & Sting Risk

The wasp that hunts black widows — and almost never bothers people

Mud daubers in southern and central New Hampshire

How to identify mud daubers — and tell their mud nests from paper wasp nests

Black-and-yellow mud dauber

Waist (petiole)

Legs

Body (overall)

Abdomen

Common look-alikes

Eastern yellowjacket (Vespula maculifrons)

Blue mud dauber (Chalybion californicum)

Organ-pipe mud dauber (Trypoxylon politum)

Two mud dauber species: which one is in New Hampshire?

Frequently asked

Are mud daubers dangerous to kids or pets?

Are mud daubers in New Hampshire?

Should I kill a mud dauber?

What are mud daubers good for?

Do mud daubers damage my house?

How do I tell a mud dauber from a yellowjacket?

What is the mud tube on my wall, shed, or barn?

What is the difference between a mud dauber and an organ-pipe mud dauber?

Will another wasp move into an abandoned mud nest?

Should I remove the mud nest?

Sources & further reading (8)

Wasps gone — and they stay gone.