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European fire ants invading Richmond

Spend enough time walking through McDonald Beach, and you’re likely to come across the European fire ant, an aggressive nuisance species equipped with a painful stinger that causes a burning sensation and is known to swarm.  - Martin van den Hemel
Spend enough time walking through McDonald Beach, and you’re likely to come across the European fire ant, an aggressive nuisance species equipped with a painful stinger that causes a burning sensation and is known to swarm.
— image credit: Martin van den Hemel

The European fire ant is invading Richmond, and the biologist who identified the species when it was first collected from a North Vancouver home in 2010, said holding them off has proven difficult thus far.

But Thompson Rivers University professor Rob Higgins said he’s working on a technique that holds some promise.

At just a couple of millimetres long, the European fire ant (Myrmica rubra) is a little challenging to spot, but once you’ve been stung, the distinctive, burning sensation isn’t likely something you’ll soon forget.

Dog walkers at McDonald Beach, at the north tip of Sea Island, are certainly familiar with them.

One woman, walking a large group of leashed dogs, exclaimed Wednesday afternoon that a grass-covered clearing at the eastern edge of the park is “crawling with them.”

Another dog owner said she knew her dog was stung when it suddenly began to chew at its foot.

Higgins said this species of ant can be found all over Europe, but was only recently introduced to B.C., where other species of ants and insects aren’t equipped to deal with them. As a result, fire ant colonies tend to monopolize an area, and kill off other species of ants and invertebrates.

A study Higgins did last summer with Langara College found that in places with the fire ants, “virtually all other species of ants” were displaced. Other insects, including beetles and spiders, are impacted too, he said.

The fire ants have proven a challenge to control to this point.

They’re resistant to biological controls—such as decapitating flies and fungi—as well as pesticides, he said.

In the U.S., pesticides were discovered to become ineffective after just a couple of months.

With just five per cent of a colony out foraging at any given time, when those foragers don’t return, the colony’s queens (which can number up to 20) are equipped to increase egg laying.

The weather isn’t helping either.

Higgins has found that once a colony has become winter-hardened, they can survive temperatures as low as minus 15 Celsius with no mortality

Aside from McDonald Beach, Higgins said the fire ant was also found in a residential area of Richmond, but wouldn’t disclose that location for privacy reasons.

This species of fire ant, which is equipped with a stinger and injects a venom that causes a burning sensation that lasts about 30 minutes, likes heat and moisture, and colonies are established in soil, about eight inches underground, and usually under stones or fallen trees.

High numbers of stings can lead to severe medical reactions, especially in infants, neurologically-compromised people and the elderly.

While in Europe, there’s about one colony—comprising roughly 1,000 workers and up to 20 queens—every 10 square metres, in the Lower Mainland, as many as four colonies are found in a single square metre, he said.

Higgins said fire ants don’t normally occupy homes, but have been known to establish colonies along foundations, and get into homes for foraging purposes through cracked foundations.

This spring, Higgins is hoping to introduce trap nests, essentially plastic containers containing moist soil that’s buried in the ground with a rock placed on top, hoping to lure colonies to relocate inside, and then remove them for destruction purposes.

Colonies relocate, especially in the spring, searching for warmer and moister environments.

Preventing the fire ants from spreading is another priority.

And with that comes raising public awareness about the role residents can play in ensuring they don’t unwittingly spread the ants to other neighbourhoods and communities.

People are discouraged from removing soil and plants from areas where the fire ants have established themselves, such as McDonald Beach.

For the home gardening and horticulture industry, co-operation is also necessary, he said. At garden stores, staff and customers need to keep a close eye on product, to ensure fire ant colonies aren’t moved inside potted plants and trees.

Higgins said he’s been working closely with the City of Richmond about the presence of fire ants and devising a strategy.

Higgins said knowing precisely where fire ants have been spotted is helpful too. Anyone who wants to share information about where they’ve been spotted is asked to e-mail him at rhiggins@tru.ca

Once the fire ants have been plotted, he’d like to research if there are natural barriers in place that prevent their spread.

As well, parks that sit adjacent to where fire ants have been colonized, need to be monitored closely.

Higgins warns on his website: “If these ants get into parks and campgrounds, the can render them effectively unusable.”

City of Richmond spokesperson Kim Decker said the city is working closely with professor Higgins and the Invasive Species Council of B.C. on ways to deal with the fire ant situation.

Tips to avoid being stung

• keep moving, as remaining stationary can allow the ants to crawl up shoes and legs

• be careful where you stand, as this species of ant is aggressive and known to swarm when disturbed

• wear protective clothing during outdoor activities, such as boots, and tuck pant legs into socks

 

This dead snake attracted several European fire ants, which at a couple of millimetres long are hard to detect, but which dog walkers familiar with the area are all too familiar with, and wary of.

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