There’s something in the air this time of year. The sunshine is especially golden, red leaves are beginning to appear on the trees, and “Mosquito Hour” is reduced to “Mosquito Five Minutes.” It’s easier than ever to spend quality time outside with loved ones. There is love in the air, as some species prepare for winter by finding a mate before they hibernate. Many insects do this, including bees and bald-faced hornets.
Bald-faced hornets (Dolichovespula maculata) are ¾ inch-long wasps with black and white markings. The queens are the only ones that survive the winter, and now is the time when they are preparing for hibernation. Newly-hatched queens will mate with a male drone, and then the mated females will burrow into the ground, an old tree stump or squeeze behind a nice comfy flap of tree bark to spend the winter. All the rest of the colony (the male drones, female workers and old queen) die of old age or freezing temperatures.
Late fall is a good time to find the abandoned nests, long after all the nest-defenders are gone. The nests are as large as a basketball, shaped like a football, and usually attached to a twig in a shrub or tree. If you cut open an abandoned bald-faced hornet nest you’ll notice several papery layers of insulation surrounding the nursery combs. Paper wasps have similar habits, but their nests are open, with no insulation surrounding the combs.
Early next spring, in April or May, the queens will emerge from hibernation and begin the life cycle anew. Each queen will make her own nest by chewing up wood fibers and mixing them with her sticky saliva, making paper. The colony starts with just a few paper cells arranged in a honeycomb-like structure attached to a twig. The queen lays one fertilized egg in each six-sided cell, and once the eggs hatch she feeds the larvae with a high-protein baby food of chewed up insects. At some point, when the larvae have had enough, they spin a white silk roof over their cell to pupate. They later emerge as infertile female workers.
Once the queen raises the first generation of workers, they take over all the nest-building and child-rearing duties, and she spends her time laying eggs. As adults, the hornets don’t grow, because their exoskeleton is hard and fixed. They mostly eat sugary foods like nectar and rotten fruit for energy.
When workers are in the nest they shiver to produce heat. The heat is retained by the layers of insulation, allowing the larvae to develop more quickly, and the adults to stay at the 95 degree body temperate required for fast flight and nest defense. If you accidentally bump a nest in the summer, the thin paper shell will rip and hundreds of hornets may fly out to sting you. They don’t have barbs on their stingers, so they can each sting multiple times. This fierce defense is necessary, because the larvae in the nest are tasty, protein-rich treats for birds, bears, foxes, skunks, and raccoons.
In late summer and early fall the queen lays two different types of eggs. One set will be unfertilized eggs that hatch into male drones. Wasps, bees, and ants don’t have X and Y chromosomes to determine sex like we do. Instead females hatch from fertilized eggs, and are diploid (having two sets of chromosomes like us), and males hatch from unfertilized eggs, so are haploid (having only one set of chromosomes).The final set of fertilized eggs pupates into fertile females with more fat stores and chemicals to protect them against freezing damage – the new queens. They mate with a drone and then hibernate until the next spring, when the cycle begins again.
Spring and fall are the seasons when we are reminded again and again of all the cycles present in nature. As the heat subsides, the humidity falls, and the kids go back to school, take a deep breath and appreciate the beauty of the season.
For over 44 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M. The new exhibit, The Joy of Birds: Feathers in Focus opened in May, 2011. Find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Also discover us on Facebook, or at our blogspot, http://cablemuseumnaturalconnections.blogspot.com/.