When a yellowjacket is smashed, its venom sac releases an alarm chemical that alerts nearby guard wasps to come and defend, according to Peter Landolt, a research entomologist with the U.S. Department of Agriculture in Yakima and adjunct faculty member at Washington State University. Even the process of stinging releases the signal, inciting more wasps to give chase.
With 15 different species in Washington state alone, wasps are seen hovering over grass, landing atop bird feeders and scuttling across picnic tables more and more at this time of year. They’re not seeking people to attack, explained Landolt. Instead, they’re searching for food and water for the developing larvae being cared for at the nest.
“August and September are typically when encounters with humans go up. I like to tell people that it’s helpful to understand why wasps behave the way they do to reduce those kinds of encounters,” said Landolt, who in 1987 discovered wasps’ nifty alarm chemical signal – a type of pheromone. He has since designed commercial and do-it-yourself traps with food-based chemical attractants to reduce wasp numbers in areas where people congregate.
Name that wasp
Paper wasps, yellowjackets and bald-faced hornets all produce new colonies each year. Except for a few wasps that might sneak into the warmth of a home, only the mated queens survive the cold months of winter.
Here to today, gone…
“Come winter, they’ll be gone,” said Landolt.
So if possible, keep your cool in their presence and let them eat your insect pests. However, if wasps pose a stinging risk because of their nests’ proximity to people, “by all means, do something about it,” he said.