Indications of fall are all around. Goldenrod is blooming, leaves are falling, pumpkin spice lattes are being served at your favorite coffee shop, and stinging insects seem to be everywhere. Just when we are looking forward to getting outside to enjoy the cooler days and outdoor events like the State Fair or tailgating at our team’s games, along fly these “spicy little sky daggers.” I borrowed that term from one of my military buddies, who, despite his bravado, is surprisingly fearful of these zippy picnic prowlers.
So why is it that we don’t normally see hornets, wasps, and yellowjackets at our spring outdoor events? The answer lies in their biology. These insects are “primitively social.” They build nests as a family group, with a queen that lays eggs and workers that forage for food, protect the nest, and tend to their young, but unlike ants, termites, or honey bees, their colonies do not last through the winter. Each year, just before the first frosts, social wasp colonies produce new queens and drones (males) that will mate and disperse from the colony to find sheltered hiding spots and diapause (a period of suspended development) through the winter. The mated queens will burrow into leaf litter and soil or under rotting logs or wood piles where they are protected from freezing temperatures. In the spring, the queens awaken to start brand new colonies, but they do not yet have workers to help. They must build the nest, collect food, and defend the brood all by themselves, so in the spring, there are very few social wasps flying around. Once the queens have raised workers, they switch to just laying eggs, leaving the workers to handle the rest of the colony tasks, and the colony grows exponentially through the summer. About this time of year, the colonies reach maximum size, with hundreds or thousands of workers traversing the landscape searching for as much food as they can find because they now are beginning the process of raising queens that will start next year’s colonies.
Red wasp, yellowjacket, and muscoid fly feeding on rotting pears.
Ben Powell, ©2024, Clemson University
Social wasps need both sugary sweet fluids to power flight and protein to feed their young. In nature, they will eat sugars from ripened fruits or nectar from flowers, which makes them fairly important pollinators, but it also means that they are attracted to our sugary soda cans and sweet desserts, which is why you often see these insects around trash bins. It is also why you should pay attention when taking a sip of soda at your next tailgate party (Go Tigers!) They also collect meat to feed their young. They mostly collect other insects, such as caterpillars or beetle larvae, which makes them beneficial predators of pest insects, but several species, such as southern yellowjackets, will even visit dead fish, roadkill, or your backyard barbeque, which can be quite a nuisance.
Bald faced hornet nest.
Ben Powell, ©2024, Clemson University
One of the most intriguing behaviors of social wasps is how they construct their nests. Most chew wood fibers or tree bark into a papier mâché-like paste, which they form into a series of cells that resemble the comb honey bees build, but honey bees use wax they secrete from their bodies to build their comb. Each social wasp species builds distinctive nest designs. Umbrella wasps, Polistes spp. (aka red wasps) build very simple single layered nests that are exposed, whereas bald faced hornets, Dolichovespula maculata, and yellowjackets, Vespula spp. construct intricate multilevel combs shrouded in an envelope. Where they choose to build their nest is also species specific. Yellowjackets are attracted to the urine odors in old rodent burrows which is why they mostly nest in the ground, although aerial nests do occur, especially if a squirrel or bird has been using a small tree hole for shelter. Bald faced hornets tend to build their distinctive teardrop-shaped nest on open branches in hardwood trees, and umbrella wasps will attach their exposed combs under the eaves of buildings or lower tree branches where they are sheltered from rain.
Yellow legged hornets hawking bee colony near Hilton Head, SC.
Ben Powell, ©2024, Clemson University
Social wasps are of particular importance this year for two main reasons: 1) the introduction of the yellow legged hornet and 2) storm recovery from Hurricane Helene. The yellow-legged hornet, Vespa velutina, is an Asian species of hornet that was first observed near Savannah, GA in August of 2023. Despite efforts to eradicate it, it has spread into South Carolina, where hornets and nests have been collected in 2024 in Jasper and Beaufort counties. To date, Clemson’s Invasive Species Program within the Department of Plant Industry has removed five nests near Bluffton and Hilton Head. While it is not expected to pose a significant health threat to people, this particular species is a serious concern for beekeepers, because it has a particular fondness for honey bees. The yellow legged hornet is nicknamed the “Bee Hawk,” because of its peculiar “hawking” behavior, where it hovers near the entrance of the bee hive, snatching forager bees returning to the colony. When hornet pressure is high, honey bees have trouble collecting enough food to maintain the colony through the winter. The “bee hawk” caused colony losses in Europe after it was accidentally introduced to France in 2004. To help our beekeepers, we are asking anyone, especially residents in the Lowcountry, to report suspicious hornets to the yellow legged hornet response team at Clemson Department of Plant Industry Yellow Legged Hornet and South Carolina Yellow Legged Hornet Photo Reports.
Secondly, stinging insects, especially yellowjackets, have been reported as hindering clean-up and recovery efforts after Hurricane Helene. First responders and utility crews have encountered disturbed colonies as they work to remove downed trees and restore utilities across the upstate and throughout Appalachia. Because the storm felled trees over a wide area right when yellowjackets are at their peak, colonies have been covered with debris or displaced and have been very defensive, which means we probably should discuss how to avoid or deal with being stung.
Stings from social wasps are designed to accomplish one thing, and that is to deter predators or animals that might damage the nest. Foraging wasps are not likely to sting while searching for food, so tailgaters should not fear a wasp that is investigating their party. It is only if the insect is trapped or injured that it will sting while it is out foraging, so try to avoid swatting or slapping them. If you encounter a nest, then avoidance is key. Most wasps will not become defensive as long as you keep your distance and avoid jostling the nest. Unfortunately, in the case of ground nesting yellow jackets, it can be very difficult to notice where the nest is, and accidental disturbance is common. If you are confronted with defensive wasps, get low, protect your eyes, and create distance. Stinging wasps have the tendency to be attracted to the head of the predator and will attempt to sting around the mouth and eyes. Getting low and protecting your eyes reduces stings to the head and face, and creating distance will put you out of the perimeter of defense.
If you are stung, know that wasp venom is not like spider or snake venom. It is designed to cause intense pain but rarely causes tissue damage, long-term injury or scarring. Everyone is allergic to wasp stings because the natural response of the body is to flood the area with fluids to dilute the toxin. This results in localized swelling, redness, and itching in addition to the pain. As long as the reaction is localized to the sting site, then most will recover completely within a day or two after the sting. Fewer than 5% of people suffer from anaphylaxis, which is a systemic reaction to insect stings where swelling can occur well away from the sting site. If you are stung and you experience severe headache, swelling of parts of the body that were not stung, shortness of breath, racing heart rate, or difficulty breathing or swallowing, then seek medical attention immediately.
Despite these concerns, social wasps are among nature’s most beneficial organisms. True, they are well equipped to defend their nests and will sometimes try to join in on our outdoor parties, especially in the fall, but their services as pollinators, predators, and food for reptiles, amphibians, birds and mammals make them important contributors to South Carolina’s natural beauty. They deserve recognition for being papier mâché powerhouses.
