European fire ant, Myrmica rubra
Since I'm referring to this ant as an invader to North America, I'm choosing to use the common name suggested by the University of Maine. There they study this insect, which is simply referred to as the common red ant over in Europe--even its scientific name translates to that. Scientists in Maine suppose that these creatures have become established in Quebec and New England by way of unintentional importation. A breeding fragment of a colony can easily stow away in the roots of a tree, wrapped in burlap and shipped from a nursery across the Atlantic. The worry now is that further transport of potted plants, mulch, and other materials will spread the ant to other areas. Ant colonies generally develop individuals which have wings and can breed, but so far the European fire ant has not been observed to do so in North America.
Why all the concern? Besides the fact that they may displace native ant species and prey on other native animals, these ants--to repeat the phrase that a coworker used when first reporting the ant to me--"sting like a bastard." The "fire" part of the name is not just their color, but the burning sensation you feel when these aggressive insects decide to defend their colony. Taking these pictures I got off easy--a single sting on the tricep that felt like I was whacked with nettles. A landscaper who received many stings described the experience as "much worse than yellow jackets." Apparently the effect of the sting varies in intensity depending on individual sensitivity and amount of venom injected.
I have an email alert for news and blog postings about the species, in the hopes that an effective control method will be developed and reported upon. The vast majority of emails are blog posts by enthusiasts who keep this species in captive colonies. Often they are video posts, sometimes they are husbandry discussions on bulletin boards, but a disturbing amount of them are posts about people selling and trading ant colonies. It would not surprise me if this species became a problem far from the east coast through an accidental release, or a discarded colony. The other category of news information about Myrmica rubra is the publication of research articles about them. They are a frequent subject, not as an invasive pest usually, but because of the fascinating interactions they have with other native European insects. There are several species, most famously a small blue butterfly, that use chemical disguises to produce young within the ant colony itself. The ants will rear caterpillars as they would their own larvae, stupified by the pheromone signals emitted by the invading insect.
I should hasten to add that there is no relation between this ant and the much more famous "Red Imported Fire Ant" Solenopsis invicta, which is native to South America. The European fire ant has some ecological advantages when compared to the RIFA. M. rubra is more tolerant of cold temperatures, clearly. The European ant also creates multi-queen colonies, with fertile females sometimes numbering in the hundreds in the largest supercolonies. Sister queens living alongside one another isn't unheard of among ants, but in M. rubra these many queens may not even be related to one another. The potential for population density is conceivably limited only by food and shelter resources.
The European fire ant is a generalized scavenger, feeding on nearly anything edible, including high energy plant-based foods, live animal prey, and aphid honeydew. This presents a challenge for bait-based pest control; while the ants readily take insecticide baits, they have many other food sources to choose from and will not be wiped out by a single bait application. A very low concentration of boric acid (a relatively safe and environmentally friendly insecticide) must be used to avoid killing the workers before they have a chance to feed the brood. Baits designed for Red Imported Fire Ants seem to be somewhat effective, too. Broad insecticide spray treatments have been shown to be ineffective, as the bulk of the colony is cryptic, and will rebound from the survivors. The surface of the colony is easy to find: under rocks, amid the roots of shrubs and trees, and in mulch and other debris. Typical habitat in North America includes most outdoor man-made landscapes: gardens, lawns, landscaping edges, and so on.
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University of Maine EFA management advice.
Thorough and terrifying information from New Zealand.
Global Invasive Species Database. Most of the information here is taken from the New Zealand site above. Good launching point to find other invaders.
UMaine, again. This link includes a form to send with your collected ant sample to see if it is the EFA.