European Fire Ants

One of the world’s 100 worst invasive species—European fire ants (Myrmica rubra)—is emerging in areas of BC in alarming numbers, packing a punch with its surprising swarm and sting.

Provincial biologists first confirmed the presence of the European fire ant in BC in 2010. Known populations have nearly doubled since last year, showing up in Burnaby, Vancouver, Richmond, North Vancouver, Maple Ridge, Chilliwack, as well as Victoria and Courtenay.

BC’s irrigated lawns and gardens, coupled with a moderate coastal climate, make for ideal conditions for fire ants to establish dense colonies. Up to four nests per square meter teaming with aggressive, swarming ants have been reported.

The European fire ants are reddish in colour, with some displaying a darker head. They nest in lawns, raised garden beds, often under rocks or within wood debris. Colonies do not form a large mound on the ground, making them difficult to notice.

Under certain conditions, the European fire ant reacts quickly and aggressively to ground disturbance, delivering a painful sting described to be nearly as painful as a wasp sting. Often victims are swarmed and stung before realizing they have disturbed a nest, and suffer from painful welts and swelling, and in rare cases, allergic reactions. The ant also has the potential to impact agricultural crops, as they have in California, and may displace native ants in their natural environment.

New colonies establish near the original site in a process called “budding” as one or more queens and a group of workers leave to start another colony. If fire ants invade a recreational area—such as a park or golf course—the area may be rendered impassable, and unsuitable to the public.

Due to multiple queens in every nest (up to 15), eradication may not be possible. However, with early detection, the nests can sometimes be destroyed with multiple baiting using boric acid. Commercial pesticides are not an effective treatment.

The invasion of European fire ants is a public safety and ecological concern, and can potentially affect property values. A report by B.C. Ministry of Environment's Ecosystems Branch—a team of ecologists, environmental economists and city planners—speculates that European fire ants could end up costing the province more than $100 million annually in 20 years, not including decline in property values of affected homes.

Work is underway by The Invasive Species Council of BC, in partnership with the Real Estate Foundation, to create a fire ant advisory council to consider how municipalities can develop tools and resources to address invasive species in their communities.

European fire ants are introduced and spread through garden and landscape materials, such as potted plants, mulch and soil. Reducing the impact of this aggressive invader will take the coordination and efforts of all homeowners.

To minimize the impact of fire ants and help stop their spread:

  1. Refrain from moving soil, mulch or plants from infested areas; instead, bait colonies with boric acid. Experts also advocate soaking roots of purchased or traded plants in cold water before transplanting.
  2. Make your property less attractive to European fire ants by reducing areas of exposed soil or yard clutter, especially scattered rock and woody debris.
  3. Raise awareness in your community. European fire ants can be confused with native ant species that are not harmful to the environment.

European fire ants are fairly small, about 4-5mm, and can be confused with thatching ants (Formica ravida), and Manica invidia, which are larger (Thatching ants 8mm; Manica invidia 5-7mm). The European fire ant is identifiable by its two waist segments (our native ant only has one), and two backward pointing spines and stinger (visible with a magnifying glass). Residents trying to identify fire ants on their property can send a sample for free identification through the Ministry of Agriculture.

Further Resources: 

Sources: BC Inter-Ministry Invasive Species Working Group
Photo: Flickr 

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