A beautiful black and yellow mud dauber prepares to gather mud at the water’s edge of the mighty Shenandoah. Image credit: Paula Shrewsbury, PhD
By building a nest inside a woodstove, a mud dauber unwittingly helped create an interesting piece of pottery.
This week we dip into the mailbag to see how ill-fated wasps can help create fascinating pottery when they select poor locations to build their nurseries. While performing an annual tune-up of a woodburning stove, an inquisitive homeowner discovered a strange foreign object in the bowels of the firebox. His first thought was that this might be a piece of cast iron slag or creosote accretion. Upon closer examination, he astutely identified the mass as a mud dauber nest that had been “fired” by the heat of his stove. With some remorse, he reflected on how many trips the mother wasp must have made up and down the fifteen-foot stovepipe to construct the nest, only to have her youngsters roasted alive in a stove. Well, to learn a little bit more about industrious mud daubers, let’s revisit an episode from 2017 about one of my favorite wasps, the black and yellow mud dauber.
After provisioning all the cells with spiders and laying an egg in each cell, a mud dauber puts the finishing touches on a nest.
“On a steamy day in Maryland, nothing beats a trip to one of our mighty rivers, the Potomac or Shenandoah. After a fierce hike on a scorching day, I stopped by the Shenandoah at Harper’s Ferry to cool my hot feet. Along the riverbank dozens of mud daubers discovered what must have been the perfect formulation of clay, minerals, and water to construct pottery homes for their young. In an amazing display of harmonized movements, mouthparts and legs of mud daubers formed spheres of glistening mud and airlifted mud balls to nearby human-made structures. Corners of window frames and doorjambs were perfect locations out of the rain to build pottery homes for their young. Nest construction by Sceliphron caementarium centers on creating a series of hollow mud chambers, provisioning each chamber with food, depositing an egg in each chamber, and sealing the mud tubes with a cap of mud to keep out weather, but more critically parasitoids and predators intent on making a meal of mud dauber larvae.
Watch as mud daubers use clever jaws and legs to shape mud into perfect balls ready to be airlifted to the nest construction site.
Several juicy paralyzed spiders await the hungry jaws of a mud dauber larva inside their clay crypt.
Just what are the provisions for babes of black and yellow mud daubers? Spiders, lots of them. Individual cells of mud daubers may contain as many as 25 spiders to serve as food for a single wasp larvae. Several species of web spinning and hunting spiders have been discovered in nests of mud daubers. One might think that spiders are pretty risky food for baby wasps but mother has a way to disarm these fanged prey. Female mud daubers deliver a venomous paralytic sting to the nerve center of the spider, rendering it immobile and harmless. These spiders are the ‘undead’. Sealed in clay coffins, spiders will be consumed alive one-by-one by the developing wasp larva. When the last spidery zombie in the chamber is consumed, the wasp larva pupates and later emerges as an adult ready to find a mate, build mud nests, and capture spiders for young of her own. Unlike the venom of hornets, yellowjackets or honey bees that is meant to inflict pain on vertebrates intent on robbing nests or hives, the venom of mud daubers is designed to paralyze prey and the sting of these docile wasps is reported to be mild by comparison, much like the sting of solitary bees we met in a previous episode.
Exit holes mark emergence sites of mud daubers that have completed development within mud nests constructed by their mothers.
The primary concern raised by these beautiful spider hunters is the aesthetic disfigurement of buildings where clay nests stuck on walls, doorjambs, eaves, and window frames can be very abundant. In an interesting twist to this mud dauber story, workers cleaning up a nuclear waste facility apparently found wasps gathering radioactive soil to build their nests and many of their creations were “fairly highly contaminated” with radioactive isotopes. Just imagine giant mutated wasps glowing in the dark, capturing small pets instead of spiders to provision their nests – sounds like reasonable grist for another B grade sci-fi movie about insects!” While the firing of a mud dauber nest might seem somewhat tragic, there is a reasonable chance that this nest was occupied in years past and that the larval chambers were empty. Mud daubers do not reuse former nests so maybe no carnage was involved. As our human friend concluded, he may simply be the proud owner of a “goofy conversation piece.”
Acknowledgements
Thanks to Andy Smith for sharing his story and images that inspired this episode. Paula Shrewsbury provided a great photograph of the black and yellow mud dauber. The wonderful Featured Creature Sheet “Common name: black and yellow mud dauber, scientific name: Sceliphron caementarium (Drury, 1773) (Insecta: Hymenoptera: Sphecidae)” by Erin Powell and Lisa Taylor, and “Radioactive wasp nests at Hanford reservation” by the Associated Press were used to prepare this story.