By HCW Staff
Do you feel like you’re seeing more wasps than usual? You very well may be. All wasps are more prevalent in the fall, when their summer nests are at maximum capacity and the adults have fewer larvae to care for. Adult wasps are also reaching the end of their life cycle, and their nests will soon be abandoned.
Many of the wasps you are seeing are probably European paper wasps, which we inherited from Europe in recent decades. The European paper wasp (Polistes dominulus) was first recorded in the U.S. in Massachusetts in 1981 and moved its way west, reaching Washington State in 1998. As Keith Seinfeld, KPLU News Seattle, reported in 2006, “So far there’s no sign of environmental damage done by the European wasp, and it’s not particularly aggressive—in fact it may do a little good in the garden by eating other pests.”
These paper wasps are often confused with yellowjackets, another kind of wasp, because they have similar markings. The easiest way to tell the difference between the two is by their nesting habits. European paper wasps create nests that are only one cell deep, forming a single comb and resembling an upside down umbrella. Yellowjackets create large aerial nests that are entirely enclosed in paper. Yellowjackets will also construct nests below the soil surface.
Fortunately, there are some benefits in both European paper wasps and yellowjackets: wasps eat flies, aphids, caterpillars, and other invertebrates, making them an important insect-controlling predator. “We would have serious pest problems if it weren’t for yellowjackets,” says Todd Murray, an entomologist from Washington State University’s Extension program. In fact, yellowjackets are used as biological control agents in corn, cotton, and tobacco crops. A few well-placed nests can clear acres of crops of any pests. It’s the wasp larvae that feed on other insects, supplied to them by adults. Adults feed on nectar, pollen, fallen fruit, and other dead insects.
So far, the European paper wasp has been described as docile in the Pacific Northwest. Murray says that from what he has witnessed, the wasps are only concerned with maintaining their nests. “While photographing a queen, I bumped her with the camera lens. She just shot me a dirty look and went back to work,” says Murray. “Rarely do I see aggression when I’m present around their nests.”
European paper wasps like to build nests on human structures like roof eaves, decks, overhangs, doorways, outdoor light fixtures, BBQ grills, birdhouses, mailboxes, and pipe corral or other fencing around horse paddocks. Murray recommends leaving the nests alone whenever possible, as you may actually benefit from having them around to feed on barn and garden pests.
But remember, unlike bees, wasps can sting multiple times. Some people react violently and can experience anaphylactic shock as an allergic reaction. Prevention is key for keeping wasps out of wall voids, attic spaces, tack rooms and barns. Seal any cracks, gaps, and holes to prevent wasps from entering and setting up shop. For air vents, install a wire screen to prevent wasps and other critters from entering. Studies have also shown that certain essential oils such as peppermint oil are a viable wasp deterrent (Zhang, Schneidmiller & Hoover, 2012). If you are aware of areas on your property where wasps often return to build their nests, placing a cotton ball treated with peppermint oil nearby can keep wasps from returning. If you must remove a nest, contact your local extension office for more information on the best way to go about it.
Wasps on the Trail
Because of the danger of wasp venom, it’s also important to be mindful of stinging insects while out riding. When enjoying your end-of-summer trail rides in areas where ground-dwelling yellowjackets are active, practice these rules to stay safe:
Ensure all riders in your party are aware of the risks and nature of ground-dwelling yellow jackets.
Find out ahead of time whether any member of the party is allergic to wasp stings. If so, make sure they carry an EpiPen.
While riding in a line, the #2 and #3 riders have a particular responsibility to watch for angry wasp activity. Ground-dwelling wasps are usually stirred up by the first rider, who may not see the insects. Then the angry wasps inflict their punishment on the remaining riders in line.
If anyone spots wasp activity, yell “BEES” (much easier to yell than “wasps”) and RUN! Horses stung by wasps often want to stand in the same spot and rub off the stinging insects—a bad idea when the rest of the angry hoard is still piling out of the nest. You may have to kick hard to get your horse to move quickly from the area, but it is imperative for your safety and that of others that you do so.
After you are well away from the nest area, it is safe to dismount and inspect your horse, riders, and dogs for possible stings.
Treating Wasp Stings on Horses
A few stings on your horse’s body can be soothed with cold water and a healing ointment like aloe vera gel. If your horse experiences excessive swelling, irritability, pain, or difficulty breathing, contact your veterinarian immediately. Stings on your horse’s head, muzzle, or other sensitive areas need to be watched very closely for signs of excessive swelling or other serious issues.
For more information on how to deal with wasps on horse properties and trail rides, check out the following resources:
Bee Prepared from TheHorse.com
Yellowjacket or Paper Wasp? from University of California
Zhang, Q., Schneidmiller, R., & Hoover, D. (2012). Essential oils and their compositions as spatial repellents for pestiferous social wasps. Pest Management Science, 69(4), 542-552. doi: 10.1002/ps.3411