When one of the world’s worst invasive species, the Argentine ant, showed up along Oak Bay Avenue this summer, it joined a legion of other aliens making themselves comfortable on Vancouver Island.
The tiny insects drew attention for their international fame — they now exist on every continent except Antarctica — but there are many more species that don’t get as much notice.
The Capital Region Invasive Species Partnership, a local branch of the Coastal Invasive Species Committee, has identified 78 invasive-plant species alone as priorities. Sixty-six of those have already established themselves in the region, and another 12 species are likely to establish if introduced.
In a capital city with an international airport, seaports and plenty of visitors and new migrants each year, controlling the spread of alien species has to happen locally, according to the experts.
“Victoria is a gateway to the rest of Vancouver Island — there are lots of entry points,” said Rachelle McElroy, executive director of the Coastal ISC, a non-profit body that works with municipalities across Vancouver Island and the coastal mainland to reduce the impact of invasive species.
Being a “garden city” doesn’t help: rogue seeds, insects and other organisms make their way in soil packs and other plant material — including both the Argentine ant and the more common European fire ant, notorious for its bite.
“We also have a long growing season and such a good climate; plants just want to grow,” McElroy said.
And the diversity of ecosystems in the area, ranging from freshwater and coastlines to urban areas and rainforests, means many organisms can find a suitable place to stay, according to Gail Wallin, executive director of the Invasive Species Council of B.C.
But favourable conditions aren’t totally at fault.
While some invasive species sneak in undetected on boat hulls and tires, more than 60 per cent are introduced intentionally, she said.
Some plant milk thistle for its healing properties, but fail to prevent the flowers from seeding and spreading, McElroy said.
The American bullfrog was introduced by someone harvesting frogs’ legs, Wallin said. Scotch broom spread as far as the northwestern B.C. city of Terrace, after a Scot famously planted it on his Sooke farm in 1850.
“People want to have a similar garden as they had back home, so they’ll bring the seeds over and plant them in the garden,” McElroy said. “That sense of home is associated with a lot of these foreign, alien plants.’”
Not all invasive species are created equal. The Coastal ISC ranks new species according to their negative impacts.
“You want to be looking at negative impacts in terms of environmental, social and economic impact,” McElroy said.
Giant hogweed, for example, poses a threat to human health. Contact with the plant’s sap can lead to third-degree burns.
“That creates quite a health hazard if it’s in a public park. You don’t want kids playing around that,” she said.
Same goes for the spurge laurel, which she said killed a young girl in Nova Scotia with its toxic berries. And don’t let the dainty yellow flowers of tansy ragwort fool you: It can inspire a fatal chemical reaction in horses, cattle and goats if it is accidentally mixed in hay.
Other species pose economic threats by damaging crops and property values. Victoria Pest Control supervisor Kurtis Brown said most of the calls his company receives regarding invasive insects concern structural damage. Rats are other common culprits — he referred to them as “probably the world’s worst invasive” for their widespread and historical role in damaging food sources.
McElroy gave the example of fire ants as insects that cause both economic and social damage. “They bite and sting, they can swarm your legs and they respond to any vibrations. So it basically makes your yard unusable.”
But most of the damage done by alien species is directed at the natives they compete with. Invasives like the Argentine ant are known for outcompeting native species, ultimately replacing them. Didymo, or “rock snot,” is a species of gelatinous, yellowish-brown algae that first appeared in 1989 on central Vancouver Island.
“That’s one we see in our streams that can reduce food sources for other fish,” McElroy said.
Public interest is a powerful thing and the good news is that it’s increasing around invasive species, according to Wallin.
Media coverage can help, such as the buzz that surrounded the northern snakehead fish, the quirky amphibious interloper found in Burnaby’s Central Park lagoon in 2012.
The “Frankenfish” hype resulted in important amendments to the Controlled Alien Invasive Species Regulation, she said, which makes it illegal to bring certain species into the province. New aquatic invasive species, including the snakehead fish and zebra mussels, are now classified as too dangerous.
And a new B.C. Prohibited Weed list was published the same year.
“There are more legal tools and there’s more public awareness,” Wallin said.
The tricky part, however, is follow-through, according to McElroy. The Weed Control Act, for example, requires land-occupiers to manage noxious weeds on their property. (Noxious weeds, as defined by the act, are typically non-native plants that have been introduced to the province without the insect predators and plant pathogens that help keep them in check in their native habitats.)
“By law, if you have an invasive plant that’s registered, you have to manage it,” she said. “Unfortunately, there isn’t much enforcement and that’s where municipalities come in.”
Despite the efforts of co-ordinating bodies like CRISP and the Coastal ISC, municipal responses to invasive species vary widely, she said.
Also, potentially invasive plant species are still legally sold through nurseries, so the best the co-ordinating bodies can do is encourage gardeners to prevent them from reproducing.
From Wallin’s perspective, however, the biggest difficulty is changing behaviour.
“The big challenge, which I think is really critical, is having people be more informed about the actions they’re taking so they can take more responsible actions.”
The Invasive Species Council of B.C.’s strategy focuses on creating responsible habits, rather than tackling specific species. The “clean, drain, dry” method, for example, teaches boaters how to take care of boating equipment in a way that reduces the chance of introducing species like quagga mussels and zebra mussels, which have been destructive in the Great Lakes.
“When you tell a class to sneeze in their sleeves, you’re not saying, ‘now H1N1 is here,’ you’re just saying the right behaviour is to sneeze in your sleeve,” Wallin said.
Others are working to highlight the benefits of native-plant species. The Capital Regional District, for example, offers native-plant gardening workshops, where they introduce participants to both native- and invasive-plant species, teach them how to eradicate the invasives, and discuss the best native species to plant in your garden.
“You might live in a rocky outcrop that’s dry, but someone else might live on the seashore, so there’s quite a range in terms of what’s appropriate,” said Deborah Walker, demand management co-ordinator for the parks and environmental services department.
But the overall move, as dictated by the provincial government, is toward targeting the species we still have a chance of fighting. The “Early Detection Rapid Response” strategy focuses on those plant species that have popped their heads, have a high chance of spreading, but haven’t yet.
The idea is to target species such as knotweed over the already prolific scotch broom.
“I think those of us who have been dealing with invasive species over the years, we’ve gotten smarter and more strategic,” said Marilyn Fuchs, regional parks environmental conservation specialist.
Wallin mirrored her thoughts.
“We won’t ever be able to get rid of all the invasive species,” she said. “You cannot chase species-by-species. You have to change the pathways.”
CRISP’S priority invasive plant species, drawn from the B.C. Inter-Ministry Invasive Species Working Group’s Early Detection Rapid Response Program:
Giant Hogweed
- Up to six metres tall
- Spotted stems, grooved leaflets
- Closely resembles cow parsnip
- Can cause skin burns, blistering and scarring
Blessed Milk Thistle
- Up to 2.5 metres tall
- White marbling on green leaves
- Large spiny purple flower
- Poisoning and injury to livestock
Carpet Burweed
- Small, up to seven centimeters
- Forms ‘carpet’ on turf
- Divided leaves, feathery
- Small, flattened spiny seeds
Garlic Mustard
- Mature: More than one metre tall
- Dense mats: young rosettes
- Small, white four-petal flowers
- Garlic odour when crushed
Knapweed:
- Ten to 120 centimetres tall
- Leaves: May be upper narrow and lower lobed or hairy and divided.
- Flowers white, pink or purple
Lesser Celandine
- Buttercup family
- Kidney to heart-shaped dark leaves
- Flowers March to April
- Eight-petaled stalked flowers
Yellow Toadflax
- Up to 80 centimetres tall
- Numerous leaves, one per node
- Soft, lance-shaped pale leaves
- Yellow “snapdragon” flowers
Dalmatian Toadflax
- 60 to 120 centimetres tall
- Numerous stems
- Light green, waxy leaves
- Heart-shaped with pointed tip
- Yellow with orange “snapdragon” flower
Scotch thistle
- Up to three metres tall
- Woody, branched stems with spine-edged wings
- Silver-grey colour, wooly hairs
- Large violet to reddish flowers
Yellow loosestrife
- One- to two-metres tall with lance-shaped leaves
- Yellow, five-petaled flowers on tall, softly hairy stems
- Branched flowers tends to cluster on top
Knotweed
- 1.5 to six metres tall
- Lance-shaped leaves, heart-shaped leaves that are thicker and leathery or thinner and more flexible
Orange hawkweed
- Fibrous-rooted with milky juice
- Orange-red flowers on leafless stalks
- Stems with stiff, black hairs
- Long oval-shaped leaves
Policeman’s helmet
- One- to two metres tall, long slender leaves
- Pink/purple flowers
- Hollow stems, reddish pink roots