By BEV BETKOWSKI
When that itsy-bitsy spider climbs
up the spout, resist the urge to stomp it out—even if it makes your skin crawl.
The leggy bugs get an unfair
reputation as being poisonous and creepy, when in fact most of them,
particularly those native to North America, are harmless to humans and good for
the ecosystem, said a University of Alberta expert.
“They aren’t bad at all, there’s
just this innate fear we have of spiders,” said conservation biologist Jaime
Pinzon, who studies the arachnids as a U of A adjunct
professor and researcher with the Canadian Forest Service. “If you
don’t bother them, they won’t bug you.”
Pinzon, who says he’s been bitten
“hundreds of times” with no harm done by spiders in the course of his work,
notes that only a handful of the 48,000 species known worldwide—including more
than 600 species of spiders in Alberta alone and about 1,500 species in
Canada—are venomous to humans, most of them living in tropical climates.
And though some might fear climate
change could bring potent tropical spiders to North America, there’s no strong
evidence to suggest it, Pinzon noted.
“It’s too premature to say that, because there are gaps in understanding the distribution ranges of many species. There may be some species that could move northward as the climate changes, but winter is a filtering process and it is unlikely they can establish populations in northern areas. There is still much to know about whether a species’ distribution range has expanded because of climate change or because it’s just undiscovered.”
Based on his research on
Canadian prairie spiders and their responses to forest harvesting, a number of
species previously not known to be in Alberta have been discovered in the
province over the last 10 to 15 years, but that’s not unusual, Pinzon said.
“The research has been done in areas
that hadn’t been studied in the past, so it isn’t surprising to find unreported
species there. The more research we do and the more we catalogue species in
different parts of the province, the better we will understand their
distribution and the overall spider biodiversity in Alberta.”
Tropical spiders do occasionally
make it to Canada by way of shipping containers, but they can’t withstand
Canada’s cold winters, he added.
“The chances of being badly affected
by a spider bite are extremely low,” he said, adding that unless you actually
see a spider bite you, that tiny wound is more likely from a mosquito or
another type of bug bite that becomes infected.
“Spiders don’t normally bite you
just because you are around them. They are very shy and they tend to escape,
not to confront.” And only the largest ones, with bodies the size of dimes or
larger, can penetrate human skin, he added. “You’d just feel a pinch, but small
spiders just cannot puncture the skin.”
While most spiders carry venom, it’s
reserved for catching food prey, not aimed at humans, and is in such tiny doses
that it poses little harm, though people with weakened immune systems, the
young or the elderly could have a stronger reaction.
“Of course, there are species of
medical concern, such as brown recluses, which are an issue in the United
States; however, there are no confirmed reports of brown recluses occurring in
Canada,” Pinzon added.
If bitten, wash the bite and see a
doctor if it becomes tender or swollen, Pinzon suggested.
“If a bite gets infected, it’s not
likely because of the venom, but because of the bacteria the spider carries in
its mouth.”
Scary but helpful
The squeamishness some people feel
for the scurrying critters is due at least in part to the human evolution of
our perception of spiders, Pinzon believes.
“Our ancestors evolved in the
presence of spiders and most likely some of them were poisonous, so there would
have been a natural aversion to spiders, the same as to snakes or any other
venomous creature. People would have feared anything that was poisonous. That
has carried through our history—spiders are seen as bad guys, particularly in
books and movies, and that makes things even worse. And we tend to teach our
kids to be afraid of the things we’re afraid of.”
But the creepy-crawlies are helpful
to humans, Pinzon said.
“They eat a wide variety of
creatures, including flying insects like flies, mosquitoes and other bugs that
can bite you. Spiders are natural controllers of insect populations, some of
which are pests in gardens and crops. Without spiders, you’d see many more of
these bugs.”
In turn, they also serve as food for
birds, other insects and spiders, showy dragonflies and amphibians like frogs
and salamanders.
“They’re an important part of their
diet,” Pinzon explained.
They’re everywhere
We have to coexist with spiders
anyway, Pinzon added. They live everywhere except at the perpetually icy North
and South poles or in the ocean. They can withstand the coldest winter,
surviving as babies or sometimes as eggs under winter snowpack or loose bark.
There are species that overwinter as adults and are active during the whole
winter.
“We have found active spiders under
the snow even in January and February,” Pinzon said. “Native species are well
adapted and develop antifreeze in their bodies. On a warm winter day, you may
even be able to see an odd spider here or there walking on the snow.”
They’ll also be living indoors, he
added.
“To keep them out of your house is
almost impossible. Cool, dark areas like basements harbor them year-round,
even if you don‘t see them.They can crawl in through any open window, door or
small crack; they will find their way in if there’s something to eat.”
But even so, people don’t need to
worry about their homes being infested with nightmare colonies of spidey
families.
“To establish a population that
carries on year after year, you need very right conditions—enough prey and
hiding places—so even though basements are cool and damp and dark, they don’t
have those conditions.”
If you do find one inside, don’t
stomp it into lifeless mush, Pinzon said. Instead, use a piece of paper to shoo
the spider into a cup and then release it outside near a tree, bush or other
vegetation.
If possible, leave spider webs
alone, he added.
Though not all spiders build webs,
the silky structures are vital to those that do.
“The silk is the main tool spiders
have for a variety of activities, such as wrapping their prey, keeping their
eggs safe and, of course, building their webs. The silk spiders use is costly
material, because they invest a lot of energy in producing it. Since
web-weaving spiders don’t move around a lot, building a web is an expenditure.
Many species even eat their old webs to recycle the silk.”
