BC Insect Update

Aug. 25, 2015, 8:26 a.m.

Hordes of bugs north of Fort St. James turned Dave Semmelink and his band of tree planters into blood sandwiches this summer.

Mosquitoes swarmed Semmelink and his crew of 12 planters early in the morning, followed by legions of black flies as temperatures climbed, followed by a late shift of mosquitoes.

It was by far the worst season for bugs that Semmelink, 26, has seen in nine years of planting.

He resorted to pulling a bug net over his head for the first time in his planting career while his crew desperately slathered themselves with several brands of bug dope. None of them did much to deter black flies, he says.

Semmelink, who was crew foreman for Brinkman & Associates Reforestation, got reports of similarly massive bug attacks this year from colleagues across the province.

“It was horrendous,” he says. “If you weren’t moving fast enough, you just got eaten.”

Welcome to summer in B.C. — the season of the itch. It’s the time of year when human hosts roll out a blood-red carpet for gleeful swarms of biting ­buggies, whether they want to or not.

Warmer-than-average temperatures across the province this year have had widely varied impacts on mosquito populations.

In chunks of the north blessed or cursed with standing water, hot temperatures helped mosquitoes grow faster, enabling them to churn out more generations, experts say. Black flies breed in moving water, so as long as creeks are flowing, the black fly is growing.

But in Metro Vancouver, mosquito control outfit Culex Environmental says populations have declined as breeding grounds dried up.

However, there are several other species of biting and stinging insects ready to take up the slack and gorge themselves on the vital fluids of residents and visitors in the Lower Mainland. If you encounter critters as nasty as the European fire ant, it can be a grisly matter.

And the fire ant, which is an immigrant species, is being joined by other insect invaders, experts predict.

A warming climate will lure new bugs northward from the U.S., while others will catch trans-oceanic rides in cargo containers, ships’ ballasts and travellers’ luggage.

Rather than demonize insects that thirst for human flesh, entomologist Syd Cannings urges a little respect.

“They’re only doing what they’re evolved to do, and we’re doing what we’ve evolved to do — which is to resist them,” says Cannings, a research associate with the Royal B.C. Museum in Victoria.

“It’s natural for us to be at odds with each other.”

Here’s how this hot summer in B.C. has treated five species of biting or stinging insects and arachnids — and how well they’ve been getting along with humans.

WASPS

B.C.’s 17 wasp species get a bad rap as ornery nuisances poised to sting at the slightest provocation, says Nathan Derstine, a masters biology student at Simon Fraser University.

But people often mistake wasps’ curiosity for hostility, he says. Derstine points to the double standard that exists for bees and wasps.

“If bees defend a hive, it’s noble. And when wasps defend their nests, it’s somehow vicious,” he says. “It’s a shame that a lot of research has gone into figuring out new ways to kill them instead of understanding their role in eco-systems.”

While he refuses to call them cranky, Derstine admits “wasps’ threshold for aggressive behaviour is lower than for bees.” That’s partly because wasps can sting multiple times and live; bees sting once and die, he says.

A big question on the minds of southern B.C. residents is whether this summer’s drought is yielding more wasps, Derstine says. But the impact of the dry weather on wasps is mixed, he says. No one really knows how the populations are doing. What is clear is heat makes wasps more active and helps them produce males and new queens sooner than the previous year, he says.

“However, these same conditions are likely limiting their forage resources in terms of the abundance of prey insects and floral nectar,” he says.

Derstine has an offer for Metro Vancouver residents with unwanted nests. Email him at nderstin@sfu.ca and he’ll discuss picking them up and moving them to his “wasp garden” at SFU, where he studies mating.

TICKS

Ticks use human blood as a source of protein to develop their eggs. But that doesn’t mean these opportunistic arachnids enjoy our blood.

“Their preferred hosts are reptiles, small mammals and mid-sized mammals,” says Muhammad Morshed, a microbiologist and tick authority with the B.C. Centre for Disease Control. “We aren’t their preferred host. We’re their accidental host. We go into their territory so they climb on us.”

Ticks are a hardy race, coping with drought by burrowing deeper into leaf litter on the forest floor, Moshed says. As a result, B.C.’s tick population will likely remain stable this year, he says.

Two of the more than 20 tick species in B.C. carry the bacteria for Lyme disease, but the main carrier is the western black-legged tick, Morshed says. Last year, the centre recorded 10 to 12 cases of Lyme disease in B.C.

Half of these cases were caused by tick bites from outside the province — which is not surprising. About one in 200 black-legged ticks in B.C. tests positive for Lyme disease, compared with one in 40 to 50 ticks on the U.S. eastern seaboard.

Lyme disease isn’t the only pathogenic treat ticks have for humans. Ornithodoros hermsi, a soft tick in the province’s dry Interior that’s active at night, can transmit the bacteria for relapsing fever.

This is a recurring fever in which an afflicted person struggles with nausea, headache and muscle and joint pain. The centre sees five to six cases of relapsing fever a year, Morshed says.

Why do ticks exist? They’re a food source for birds, reptiles and small mammals and, of course, they house disease-causing bacteria.

To protect against ticks, experts suggest hikers tuck socks into their pants and wear high boots.

ANTS

Nature has programmed European fire ants to sting first and think second. Of the 92 ant species in B.C.’s insect kingdom, they are without a doubt the biggest pains in the human backside.

A few B.C. species, such as thatching and red wood ants, can bite but are usually just annoying, says Rob Higgins, a biology professor and ant specialist at Thompson Rivers University in Kamloops.

“The European fire ant, however, swarms rapidly when disturbed and stings,” Higgins says. “Unfortunately, it likes to live in lawns and gardens. It can make standing on grass impossible.

“This is definitely an aggressive, pugnacious ant compared with our native species.”

The fire ant, originally from Europe, arrived in the Lower Mainland 15 to 20 years ago.

Something altered the ants’ hiving behaviour after they reached North America, ­turning them into poster bugs for urban densification.

In B.C., fire ants build up to four or five colonies per square metre of soil, compared with only one colony per 10 square metres in Europe, Higgins says.

The fire ant’s sting triggers a burning sensation akin to having vinegar injected into one’s flesh, Higgins says.

“A specialist in insect venom in the U.S. tells me that the European fire ant’s venom is stronger than cobra venom,” he says. “You get so little of it you don’t get anywhere near as serious a reaction.”

Higgins is currently researching a way to get rid of fire ants by treating soil around colonies with a low concentration of the chemical permethrin.

In general, B.C.’s ant species have adapted to this summer’s drought with aplomb, Higgins says.

“They can move deeper into the soil and seem to be doing fine,” Higgins says.

“We see no evidence of colony loss. With increases in temperature, many of the colonies will grow faster.”

SPIDERS

B.C. is Canada’s spider paradise — bad news for those who fear the eight-legged creatures, but good news for their admirers.

The province is home to around 820 of the country’s 1,400 to 1,500 spider species.

The number of confirmed spider species that call B.C. home will likely rise to about 1,000 as researchers discover tiny new ones dwelling under rocks in the alpine regions, says Robb Bennett, a research associate with the Royal B.C. Museum in Victoria.

Bennett says a growing number of people are coming to see spiders as cool and appreciate their role in keeping populations of pests in check.

“There’s an upsurge in interest in spiders for spiders’ sake,” Bennett says. “The fear of spiders seems to be restricted to a vocal minority of people who tend to believe all of the misinformation on the Internet.”

Spider bites are “exceedingly rare,” Bennett says. Almost all spiders secrete venom and even the jaws of fairly small spiders can break skin if they chomp on tender areas such as the inner arm. But people are much more likely to be bitten by a neighbourhood dog than a spider, he says.

“I’ve been bitten 20 to 30 times myself and never suffered any serious consequences,” says Bennett, who has researched spiders for four decades. “A giant house spider’s bite is like a pinch to remind you they are alive and that you should let them go.”

If the possibility of being bitten by even the tiniest of spiders still spooks you, consider the risks run by inflamed spider males.

Males may be eaten after mating by a ­paramour unable to resist the post-coital cannibal munchies.

“In which case, the guy dies with a smile on his face,” Bennett says.

Among the 10 to 20 spiders that people are most likely to encounter in B.C. are the giant house spider, the garden cross spider, hobo spiders, daddy-longlegs and wolf spiders.

Many people would prefer to avoid the black widow spider, which is common in southwestern B.C. and the Okanagan. Experts say the widow is shy and non-aggressive.

But its bite, though rarely fatal, can be painful and trigger a condition called latrodectism, which is characterized by muscle contractions and vomiting.

“One little-known fact about latrodectism is that a common result in men is priapism — a painful erection that just won’t stop,” Bennett says.

“I have long been surprised that there doesn’t seem to ever have been an effort made to develop a Viagra-like product from whatever component of widow venom is the cause.”

MOSQUITOES

Low populations of mosquitoes in the dried-out Lower Mainland have saved mosquito fighter Scott McMahon from using his biggest guns this summer.

McMahon is national operations manager with Burnaby-based Culex Environmental, which is contracted by Metro Vancouver to control mosquitoes in five Lower Mainland municipalities.

In a typical year, Culex would use a helicopter to disperse 95 per cent of its non-toxic larvicide to eradicate immature mosquitoes.

“This year, we didn’t use it at all,” McMahon says. “It has been very dry.”

When the bacterial larvicide has been needed, Culex employees have dispersed it into standing water by hand or from a blower backpack.

The company monitors 500 potential breeding locations and operates a hotline for people to report mosquito troubles. Last year, the company got some 90 calls; this year, there have been 23. But this summer’s drought has not been a complete disaster for Metro Vancouver mosquitoes, says Carl Lowenberger, a biology professor and mosquito expert at Simon Fraser University.

Certain species have found “great havens” in Ladner and Delta from irrigation run-off in catch basins.

As the province’s climate warms, its southern mosquito species will likely move north.

“Not only are we going to see a shift from south to north, but also in existing areas moving higher in the mountains,” Lowenberger says.

B.C. is home to the mosquito types Aedes and Anopheles, which can transmit diseases such as malaria, dengue fever and chikungunya, he says. But the parasite that causes malaria is not present in the province.

Nor are the viruses for dengue and chikungunya — “as far as we know,” he says.

pluke@theprovince.com

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