Monique Keiran: Scary invaders creep in on eight little feet

In Germany this year, a woman called the police after her doorbell rang repeatedly in the night, terrifying her. The cops apprehended the culprit — an ant nest built tight into the doorbell was tripping the switch.

My friend in this part of the world experienced a similar problem. Her home-security system spontaneously and repeatedly went off over a period of several months. It usually rang during the day, when she was at work. The alarm would signal the alarm company. The alarm company would notify the police. The police would come by and find nothing amiss.

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Telephone calls and letters from the company to my friend would follow. My friend would — again and again — call in technicians to find the problem.

It turns out the problem had eight legs and a dime-sized body and liked to hide in crannies.

This prankster was a giant house spider — yes, that is its name. Every time the not-so-itsy-bitsy spider travelled across one of the alarm’s motion detectors, it broke the light beam, triggering the alarm and calling down the alarm company’s wrath.

Native to Europe, the species arrived in B.C. a century ago. Back then, nobody thought to be concerned about invasive species, and now nobody knows how the spider’s introduction affected native species. Scientists today, however, believe this non-native spider might be keeping in check another non-native arachnid, the aggressive hobo spider.

Arthropods rarely come calling in the human-approved way, and other non-native bugs are also trying to make our home theirs.

Fortunately, the Argentine-ant nest found this year in Oak Bay is nowhere near the size of some of the nests the species makes. One stretches 6,000 kilometres along the Mediterranean coast — or the distance from here to New Brunswick.

Just think — if the Oak Bay mini-colony grows unchecked, we can anticipate it spreading up and looping back along the coast. A nuisance and an ecological threat, Argentine ants are considered fair-weather insects. They die at below-zero temperatures. Here in the capital region, however, we experience few severe frost days. This means ants with queens in nests against heat-leaking foundations or other warm locations may survive.

Another recent arrival causes greater worry. First detected in B.C. in 2010, infestations of European fire ants have been found from Chilliwack to North Vancouver on the mainland, and in Courtenay and the Victoria area.

They’re aggressive. Their stings are painful. These ants can prevent people and animals from using infested parks, lawns and gardens, lowering real-estate values. A provincial report published this year estimates the fire ant could cause up to $160 million in damage every year if it were to spread in B.C. The same report suggests the ant could spread and survive along most of our coast.

Of course, neither the fire ant nor the Argentine ant, nor even the giant house spider, got here on its own. Despite lack of wings, despite the distances, they found their way to B.C. Then they crossed the moat from the mainland and set up house within our island fortress.

Somebody brought them over.

The bugs likely hitched rides across the water in infested plant material and soil transported here for local gardens. And now that the bugs are here, those same materials serve as the main conduits for the critters to travel to uninfested territories.

Island nation New Zealand is zealous about keeping itself free of new invasive species. You can’t arrive in Auckland by air without officials scrutinizing the soles of your shoes, checking your pant cuffs and digging through your gear for soil and seeds. But to do the same to people travelling to Vancouver Island would be costly and ineffective.

Too much independent boat traffic and island-hopping occurs to gate-keep the island.

And so the insects invade.

And they don’t normally ring the doorbell to announce their arrival. By the time we notice them, they’re usually here to stay.

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