Conditions ripe for annoying wasp year

Invasive European species also adds to the mix

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Islanders suspecting that picnics and patio dining seem to be more at threat from wasps than usual for this time of year are perfectly right, according to people who work around insects.

Dave French, a technician with Salt Spring-based Pest Control Services, said last week that he and his colleague James Wood had responded to 50 calls regarding wasps over the past 10 business days, and over 100 calls so far this season. That’s compared to around 100 wasp calls in total three years ago, and still plenty of time before things die down in the fall.

“With the weather we’ve had and the weather we’re expected to have, I suspect it’s going to be a really big season, right to the end of the season,” French said. He explained Dolochovespila arsenaria or yellow jackets are the most common wasp species seen on the Gulf Islands, followed by bald-faced hornets and mud daubers. 

“Hornets are very aggressive and territorial. If you get close to them, they will attack you,” French said. “We don’t see a lot of them but when we do it’s usually a very large, very well established nest.”

The technicians have noticed the more common yellow jacket nests reached a size at the beginning of July that isn’t usually seen until later in August. French said conditions such as the combination of heat and moisture over the early summer may have created the perfect conditions for populations to thrive.

“People are watching the nests grow, and when they decide to do something about it, they’ve grown to the size of a beach ball,” French said.

“Wasp populations are on seven-year cycles. Looking at our records, we’re in year six — so next year we could be in for even worse,” he added.

Linda Gilkeson is a local master gardener and an entomologist who at one time worked for the provincial government promoting programs to reduce and eliminate pesticide use. She said insect populations like wasps naturally fluctuate, and can be different on different parts of the island.

“To me it’s a wonderful year, because it means there are no caterpillars in the garden. I have nothing eating my cabbages this year,” Gilkeson said.

Gilkeson suggested one reason people might be noticing more wasps in general is because European paper wasps have recently moved in. They look very similar to yellow jackets when flying. They are solitary insects, however, and don’t nest together in social groups. They don’t have a colony to protect and therefore don’t pose much threat.

Native wasps are beneficial insects, despite their annoyance to humans. They act as pollinators and help protect crops from the insects they eat. However, the stings can be harmful, especially to small animals and children, and those bitten repeatedly can get more sensitive to the venom over time.

Wasps commonly build nests on the sides of buildings, so one way to prevent a large colony is to walk around the home often in the spring. French said homeowners can safely knock down nests around the size of a golf ball to grapefruit. He recommends wearing a beekeeper’s hat with a mesh veil and several layers of loose clothing. If someone is using an aerosol wasp killer, they should be sure to wear a double-respirator because there are pesticides that humans should not breathe in.

If a wasps’ nest is located in a tall tree or somewhere further away from the house, French recommends just leaving it alone. Nests made in the ground often pose the most danger and should be dealt with, however.

For more on this story, see the August 14, 2019 issue of the Gulf Islands Driftwood newspaper, or subscribe online.

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