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Column: Extinguishing the European fire ant invasion
As an aggressive invasive species, European fire ants are a serious nuisance on many fronts.
They swarm and deliver a painful sting that, while not life-threatening, burns then itches for days and can trigger swelling or a possible allergic reaction. They colonize in multiple nest densities in a process called “budding” in which new nests are established close to each other in a very small area (maybe a single square metre) and each colony has multiple queens. They like warm, moist conditions and favour urban areas, lawns, and city parks where they capitalize on ground heat and dampness from lawn irrigation. Given their nest densities, they are extremely hard to get rid of, resist pesticides, and render infested grassy areas unusable by the public and pets.
According to the Invasive Species Council of B.C., European fire ants are among the 100 world’s worst invasive species and they are emerging in alarming numbers in mild, damp coastal regions of the province.
They have been found in Vancouver, North Vancouver, Burnaby, Richmond, Victoria, and Courtenay and they have been confirmed in Chilliwack. While, according to the SCBC, they were confirmed in B.C. in 2010, they have likely been here for a decade and known populations have doubled in the past year or two.
These ants are native to Europe and Asia and were brought to North America, specifically the Boston area, around 1900. They were reported in Quebec in 1915 then about 40 years ago expanded their range to Ontario.
Like many invasive animals, these insects become dominant in the areas they invade. They displace native ants that are valued for their ecological usefulness such as seed dispersal, pollination, and as part of the food chain. Fire ants protect destructive aphids as the insects like the honeydew the aphids produce. They are capable of actually farming aphids and the carbohydrates in the honeydew they consume provide greater growth of the ants and their colonies, increasing competitive performance and allowing them to out-forage native ants. Where there are high densities of fire ants, there are high densities of aphids which themselves are a serious pest for many horticulturalists.
“These ants have been in B.C. at least 10-15 years,” said Dr. Robert Higgins, Biological Sciences, Thompson Rivers University in Williams Lake. “They are very problematic for young children. The presence of these ants makes it impossible for young children to play on the lawn. Lawn maintenance can be difficult. We had one incident several years ago in Vancouver when a man had to abandon his lawn mower when cutting the grass.”
Higgins said that the ants are also an issue for dogs when playing on the lawn or being walked in parks. Subsequent swellings from stings were at first treated as infections and administered antibiotics instead of anti-inflammatories.
Given how difficult it is to eliminate fire ants, Higgins is researching control methods.
“We need to look at control options,” he said. “We have taken advantage of the lessons learned elsewhere. We know that pesticides do not work. We are looking at baiting with a container to lure in whole colonies. Then we can destroy the ants.”
There is an urgent need to get ahead of this pest. Our mild, damp climate creates perfect conditions for this ant to get firmly established. They can then be easily spread by the movement of contaminated soil, mulch, or potted plants between gardens, community plots, parks, or nurseries.
Given the problems these ants present, Higgins is optimistic that more research funding will be made available from the provincial government this year.
If you suspect you have these small, red, twin-waisted ants on your property, call Dr. Higgins for advice at 1-250-392-8106.