Making the most of the last weeks of summer in Canada, many will have picnics, barbeques and other outdoor events. Experts say they should expect some uninvited guests.
These pests are attracted to sweetness and can be seen buzzing around food or garbage and sometimes make a nuisance out of themselves with their stingers.
They're wasps, and Canadians may notice an increased presence of the irksome insects this month.
WHY ARE THERE MORE IN AUGUST?
Like bees, the wasp lifecycle starts with a female that lays eggs. The offspring then becomes the "worker force."
Wasps make nests in the spring, according to Jason Gibbs, an associate professor of entomology at the University of Manitoba, and develop the colony as the summer passes.
"Yellow jackets, in particular, can tend to get some really large colony sizes. So they're just accumulating more and more workers as the summer progresses," he said. "That's why we get this impression 鈥� which is true 鈥� that there are more wasps later in the summer than there were in the beginning."
WHAT KIND OF WASPS ARE IN CANADA?
Gibbs said wasps can be categorized broadly into two sections.
"There are lots of different kinds of wasps that we have," he told CTVNews.ca in an interview. "Some of them are solitary and those are the ones that we don't tend to notice. But there are also these social wasps, these are the yellow jackets, the hornets and paper wasps."
The "social" wasps are the ones that visit campgrounds and patios and "conflict" with humans more often.
There are many different species of wasps in Canada, some of which are not native to the country, according to Matthias Buck, the assistant curator of invertebrate zoology at the Royal Alberta Museum.
Hornets, a close relative to yellow jackets, are native to what he called the "old world," but can now be found in Canada.
"The European Hornet occurs on the Niagara Peninsula and a little bit into how the Haldimand-Norfolk Region (in Ontario) and the eastern part of Ontario, but for some reason, it's not really in southwestern Ontario," Buck told CTVNews.ca in an interview.
The European Hornet can also be found in Quebec but not further east, he said. Yellow jackets are "widely distributed."
"We have the German yellow jacket in Canada, which is a European species that was accidentally introduced a long time ago," Buck said. "Those species will both hunt for prey, but they will also scavenge, they also visit dead animals and will so have a broader spectrum broader food spectrum."
"We have a couple that are northern species鈥� Some of them range quite far north, like I've seen records from Iqaluit, so even some of the species are able to live in an Arctic climate," Buck said. "Then we have a couple of species that are more restricted to the east and we have a couple of species that are western, but a lot of species have sort of have a transcontinental distribution in Canada."
Gibbs says finding the nests is the best way to figure out what kind of wasp is crashing your party.
Paper wasps have an open comb that people can see hanging underneath eavestroughs, whereas hornets form hives in trees and bushes. Yellow jackets prefer nesting in the ground or within a crevasse of a structure.
WHERE TO FIND WASPS, AND WHAT THREATENS THEM
Wasps are pollinators like bees and butterflies, which means they play a positive part in ecosystems.
However, similar to other pollinators, their biggest threat is habitat loss.
"Some of these other wasps are going to have very specific habitat requirements. They might have particular hosts insects that they feed on, they are not a generalist," Gibbs said.
Yellow jackets in particular can thrive in the Canadian summer due to their flexibility in habitat. Gibbs says garbage cans are "great" for them.
"Whereas some of the other wasps might need this particular type of moth larva to feed on or鈥nly like to live in stone dunes," he said.
Depending on the species of wasp and the environment, some prefer cities over others.
"If you're in Toronto, you may be in an area where there are lot more of these social wasps that are sort of coming and sort of invading your space," Gibbs said. "Whereas maybe in Sudbury, (Ont.,) the wasps have more options. They're not as reliant on sort of human resources as they are in some more densely urban areas."
HOW TO DETER WASPS
Wasps are "hunter-scavengers" and like "sweet things," Gibbs said.
Decaying fruit and sugary drinks will attract them, and their buzzing around is what makes people believe they are aggressive, Buck said.
But he said that's often not the reason they may be flying around.
"They're very curious. They will examine people, so they will kind of fly around you and fly in front of you," he said. "And that looks aggressive to us because they're approaching us."
The biggest risk wasps pose to humans is when there is a nest nearby.
If you have a wasp problem, Gibbs said there are ways to build a homemade trap.
Cutting the top off a pop bottle and placing it upside down in the other half can help catch them, Gibbs said.
"Put some soapy water with something sweet (like) sugary juice or rotting fruit in the bottom," he said "The wasp will go inside that funnel, attracted to the food, and they'll get stuck."
Unfortunately, these homemade traps can catch species other than wasps such as butterflies.
If there's a wasp nest, Gibbs recommends monitoring the situation before reacting. Typically, wasps leave people alone if "you leave them alone," he said.
"You know, if a wasp lands on your arm and you don't notice it, you squish it and they'll sting," he said. "But generally speaking, whenever they're out looking for food, they don't have any interest in you."
There are myths about how to deter wasps, Gibbs said, one being the fake nests people can buy in stores. According to him, there is no evidence they actually work.
"If a wasp is looking for a place to nest in the spring, the fact that there's an old wasp nest hanging in the bush from the year before, that's not gonna stop them," he said. "So hanging your paper bag that looks vaguely like a wasp nest is not going to stop them either."
