European fire ants

A new threat to pets, livestock and people
By Tom Seymour | Jul 10, 2014
Photo by: Tom Seymour Stand of mint in front of Tom's house may deter fire ant infestations.

Imagine a new invasive species that routinely attacks any creature, including people, that passes through its territory. This new pest inflicts painful bites that cause red welts that swell up and in some cases, continue hurting for hours after. Some individuals may require medical attention due to allergic reactions.

This new invasive species is here in Maine and it continues to make its way across our state. The pest in question is the European fire ant, Myrmica rubra, also known as European red ants. These are loosely related to the Solenopsis species of fire ants found in the southern states.

European fire ants differ from the southern US variety in that while the southern ants build readily-visible anthills, European fire ants build their nests under litter such as leaves, old boards and so on, out of sight and out of mind. European fire ants can invade a yard and establish a colony and no one is any the wiser. That is, until the ants bite.

According to University Of Maine Cooperative Extension Bulletin 2550, European fire ants are now established in Cumberland, Hancock, Knox, Waldo, Washington and York counties. Since that bulletin was published, colonies were noted in Penobscot County. And it’s probable that by now, these ants are in other counties as well. That’s bad news for homeowners, gardeners and anyone who likes being outdoors.

Natural deterrents

The first thing most people do upon discovering a colony of fire ants is to apply pesticides. These kill fire ants, but usually not all of them. In many cases, European fire ants return despite their colonies being treated with powerful insecticides. In order to enjoy your lawn and garden on an ongoing basis, it may be necessary to treat the colony multiple times.

On the other hand, there are some things that anyone can do to deter fire ants and to keep them from establishing nests in the first place. A few natural controls are at least somewhat effective against fire ants and these include spearmint and peppermint oils. When applied around a property, these oils may keep fire ants from colonizing. Also, spreading dry molasses, a dry feed for livestock, works too. And planting mints around edges of gardens and lawns may help to prevent fire ant incursions. Baits containing boric acid can control red ant colonies and boric acid is far less toxic than some of the commercially-available chemicals that homeowners use to control fire ants.

Also, it pays to be scrupulous about keeping yard litter to a minimum. Knowing that these ants like to hide under things is reason enough to make sure things line leaf litter, limbs, lumber, boards and other debris does not accumulate in your yard or around the house. If your place does not have all the ingredients that fire ants want or need in order to establish a new colony, chances are that they next time a bunch of fire ants come by your place, they’ll just keep passing by and not stop.

As mentioned above, mint has some degree of effectiveness in thwarting fire ants. But remember, mint is aggressive and once planted, often spreads on its own. But let me ask, which is better, a patch of mint that needs care to keep it in bounds, or an established fire ant nest? I’ll choose the mint any time.

So if planting mint, do it around the perimeter, say on the edge of the garden or on the side of the lawn next to the neighbor’s. Do this so that fire ants will just keep on truckin’ if any do happen to pass your way.

Ant beginnings

It is quite firmly established that fire ants came to Maine during the first half of the 20th century by way of potted plants from Europe being imported and planted on various coastal Maine estates. That method of colony building still accounts for new colonies popping up here and there. Knowing this, people are advised to thoroughly inspect any potted plant and if small, red ants are noted, isolate the plant by storing it in a place where the ants cannot escape to the yard or garden and contact University Of Maine’s Cooperative Extension’s Pest Management Office at 581-3880 or visit umext.maine.edu/topics/pest.htm.

European fire ants also spread on their own in much the same way that honeybees establish new colonies. That is, some ants from a colony will kidnap an egg-laying queen and move her to a new location in order to found a new site. Fire ants also have mating flights. Here, winged queens leave a nest on a colonizing journey. To my knowledge, this hasn’t happened in Maine, but did occur in Canada.

Just how painful are European fire ant bites? Unfortunately, I’ve had several encounters with these pests. Both times it was near the sea, once in Brooksville and another time in Eastport. That makes sense, since fire ants prefer humid, moist conditions. Anyway, neither of my fire ant encounters could have been predicted. The nests were not visible. Well, in Eastport I did notice that the ground was a type of fine, sandy loam, which might have tipped me off had I known what to look for.

Both times, I wasn’t aware that I had stumbled into fire ant territory until it was too late. That is, the ants were already on me and biting fiercely. The bites felt like the sting of a white-faced hornet and the pain took a long time to diminish. Quick thinking and washing in ocean water helped, but it didn’t take the pain completely away. Also, the red welts persisted for a long, long time.

If fire ants can inflict that much discomfort on an adult human, just think what they might do if they climbed on a cat or small dog. It is possible that enough bites could kill a small animal. And it’s most frightening to imagine what these biting insects could do to a small child. Clearly, European fire ants are a distinct threat to people here in Maine.

Recognizing fire ants

The most obvious way to recognize a fire ant is to get bitten by a tiny, red ant. The resulting bite will affirm beyond a doubt that this was, indeed, a fire ant. But that hardly rates as an acceptable means of identification. Fire ants do have physical distinctions that separate them from our native ants.

European fire ants are tiny, with worker ants measuring only 3/16 of one inch long. In fact, I had difficulty believing that the teeny, little red ant that bit me was really responsible for that much pain.

This requires a hand-held magnifier to see, but fire ant bodies have two, backward-pointing projections, or spines, on the middle body section. Most native ant species have only one narrow waist, but European fire ants have two waist sections. These two distinctive features, besides the painful bites, are among the surest ways of identifying European fire ants. But again, with the exception of very keen-eyed individuals, most people will only recognize fire ants after the ants have already bitten them.

Here’s another thing about fire ants. The colonies appear to be long-lived. The colony in Brooksville was still active three years after I located it (or should I say, it located me). However, several years later, it appeared to be deserted. What happened, I’m not sure. But at least this gives a glimmer of hope that European fire ants, unlike diamonds, are not “forever.”

European fire ants are just one of a host of critters new to Maine. But they are worthy of note and deserve special attention. If you think you have found fire ants, please contact the University of Maine at the above-listed address. Also, do everything possible to ensure that fire ants do not invade your property in the first place. Diligence is everything in our war against this new, insidious invader.

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