Wasp Weather War
By Dr. Stuart Mitchell
During the fall months, as average daytime temperatures cool in many parts of the US, wasp weather war is declared! In search of nutrients, potentially aggressive wasps ruin various venues and bombard backyard barbecues.
Pope Paul VI said, “Anger is as a stone cast into a wasp’s nest.” In the fall of the year, it seems many stones are thrown. Wasps are found globally. Regrettably, casualties of the wasp war experience stings that potentially result in trauma. Wasp stings from all species are the most common type of human envenomation.
Most wasps are solitary and harmless, but some social forms exhibit fierce defense behavior of their nests. In the northern temperate zone the most common social wasps are Yellowjackets, Hornets, and Paper wasps
Yellowjacket wasps, Vespula spp., have spread globally via human commerce. Strongly attracted to food and refuse, stings from close encounters result while shooing away wasps, walking barefoot near food, or swallowing wasps that have crawled into beverage cans. Yellowjackets make underground nests in rotted-out tree stumps, under stones, in mammal burrows, and within exploited architectural features.
A single colony can have a population of 10,000 sterile female worker wasps whose sole purpose is to hunt for nutrients to feed colonial larvae. Not being finicky eaters, wasps posses voracious appetites for protein and carbohydrates through spring and summer and change to sugar-rich foods such as ripe fruit and sweet soda in the fall.
A short temper combined with the ability to sting repeatedly allows Yellowjackets to be a fearsome foe. In addition, wasps have a built-in warning system that can summon the troops when needed. If one were to swat a Yellowjacket an alarm pheromone is released that brings out an army of wasps to attack the aggressor.
A wasp sting is very uncomfortable, but not life threatening, for most people. Some are profoundly allergic to a sting and experience potentially fatal anaphylactic shock. An EpiPen must be immediately employed to calm the reaction.
Wasp venom is similar to bee venom. Generally, wasp venom is not cross-reactive with bee venom allergens. Therefore, people who are hypersensitive to bee venom might be hypersensitive to wasp venom. Mastoparans cause histamine release by degranulating mast cells. Histamine, serotonin, and acetylcholine cause the pain associated with the sting.
Easily dismissed as a pest, wasps do serve a useful and natural niche. Prior to developing a taste for fruit, wasps serve a beneficial roll by consuming aphids, caterpillars, flies and numerous other pests. Wasps do not pollinate or make honey, so Honey bees score higher on our “benefit-to-humans” scale.
Paper wasps, Polistes spp., build small, inverted umbrella-shaped hanging nests (often under the eaves of houses). Stings are fairly common since these wasps are in such close contact with humans. In tropical areas, relatives to the paper wasps form large colonies and are some of the most fearsome stinging insects.
Amateur pest controllers who insist on “do-it-yourselfer” wasp control might consider placing wasp traps in the backyard, spraying the nest with soap and water, covering the entrance with an OTC powdered formulation insecticide, or sealing the nest in a cloth bag at night when the wasps are inactive. Such risk-takers might want to wear a full beekeeper protective suit. Or they can call a pest management professional (PMP) for a permanent diagnostic solution using state of the art procedures.
For the homeowner, winning the wasp weather war may be a simple surrender of avoiding bright-colored clothing or perfumes when walking anywhere wasps might congregate. Eventually, cold weather will bring a natural death to wasp colonies and ultimate victory (or at least until the following year when war is re-declared).