High fiber diets for baldfaced hornets? Nah, construction materials for enlarging nests: Baldfaced hornets, Dolichovespula maculata

Trips to the tool shed have become lively during these waning weeks of summer. Upon approaching the shed door, I am often buzzed by one or more baldfaced hornets. These intimidating predators with nasty stingers never mount an assault. Their agitation seems more like that old W.C. Fields chestnut “Get away from me kid, you bother me.” Obviously, my presence interrupts some important work underway. So, what is the deal with hornets and the tool shed? Closer observation revealed hornets gnawing on the T-111 siding of the aging shed. At this time of year, nests of many social wasps like the baldfaced hornets and their cousins, yellowjackets, are running at a fever pitch. Wasps gnawing wood began several months ago, when a single female baldfaced hornet, a queen that survived winter, began to construct a nest. Using powerful jaws, she stripped plant fibers from dead branches (and maybe my tool shed) and miraculously combined them with saliva to produce high-quality papery pulp. Her paper was shaped into chambers for brood and a weatherproof cover for her nest. Larvae that hatched from the eggs she laid were fed macerated caterpillars, flies, moths, and other insects captured by the queen. These larvae soon developed into workers that assisted the queen in gathering food, enlarging the nest, and tending to the needs of their sisters and the queen.

Over the past few weeks, a trip to the tool shed has included close encounters with baldfaced hornets. No aggression here, but it became pretty obvious that I was interrupting their business. Watch and listen to this worker as she gnaws at the wood to collect wood fibers. A miraculous concoction of wood fibers and saliva will be turned into pulp and formed into paper to build chambers for brood and an ever-expanding cover for the nest.

As the colony grew, the mother queen spent less time out foraging and more time at home laying eggs. Her daughters shouldered the load of finding dinner for their sisters and mom and gathering wood fibers, the raw material necessary for enlarging the nest. With the approach of autumn, the rapidly growing nest is in a constant state of transition. Portions of the exterior papery envelope are removed to accommodate an ever-expanding number of brood cells. By late summer the colony is in high gear, with hundreds of workers capturing prey and raising young while the queen busily lays eggs. As summer wanes, workers will build over-sized brood cells into which the queen deposits eggs destined to become new queens and males. The founding mother queen then dies, and virgin queens fly away and mate before seeking hibernal shelter under bark, inside fallen logs, or in other protected locations. There is a common misconception that the large paper nest will house hornets for multiple seasons. This is not the case. Before winter, the nest is vacated by workers, queens, and males and it will not be used again in subsequent years.

A look inside the nest reveals sisters hard at work tending the brood. Larvae squirm and poke their heads from papery cells as the workers move about the brood combs.

If you come across a large paper wasp nest, please resist any urges to investigate the nest too closely or hurl stones at it. I succumbed to this misguided temptation at age eleven and pegged a large nest with a stone from the distance of about twenty feet, a marvelous toss indeed. I was immediately greeted by an angry hornet that made a beeline from the nest to a spot on my forehead where it delivered a wicked sting, the kind of “kill shot” that snipers make in movies. I high-tailed it out of range and never again tempted a hornet’s wrath. The sting of a baldfaced hornet really packs a wallop and some people are allergic to the venom in the sting. If you are stung by a baldfaced hornet or other wasps or bees and have difficulty breathing, swelling in the face, throat, or mouth, difficulty swallowing, anxiety (beyond that of being stung), rapid pulse, or dizziness, seek medical attention instantly. If the nest is out of the way and does not endanger people, perhaps it can be left alone. These hornets consume large numbers of pests in our gardens and landscapes. If the nest is located in a place frequented by people or pets, then removal may be necessary. Professional exterminators can do the job. People allergic to stings of wasps, hornets, or bees should not undertake this task, as baldfaced hornets are quite aggressive. Potent wasp and hornet sprays are available for home use, but if you choose this option be sure to carefully read and follow directions on the label.

Acknowledgements

We thank Ivan and Patricia for providing the inspiration for this Bug of the Week after discovering a nest of baldfaced hornets attached to their home. The ever-fascinating book “The Insect Societies” by E.O. Wilson was used as a reference for this episode.

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