Maine does have fire ants, but they’re not the same species that terrorizes the southern United States. The European fire ant (Myrmica rubra) has established itself across much of coastal Maine and is spreading inland. These tiny red ants are aggressive stingers that can make yards and gardens unusable during warm months.
Which Fire Ants Live in Maine
The fire ants found in Maine are European fire ants, only distantly related to the red imported fire ants (Solenopsis species) of the South. Workers are small, about 3/16 of an inch long, and reddish in color. They don’t build the large visible mounds that southern fire ants are known for. Instead, they nest under rocks, boards, fallen leaves, logs, and other debris at ground level, making them easy to stumble into without warning.
Populations have been confirmed in at least nine Maine counties: Cumberland, Hancock, Kennebec, Knox, Penobscot, Sagadahoc, Waldo, Washington, and York. By 2002, they had already been documented in more than 20 locations along the coast. More recent confirmations include specimens from Calais and Georgetown in 2021 and Orono in 2022, showing the ants are still expanding their range, including to inland areas.
Why They Survive Maine Winters
Southern imported fire ants can’t tolerate prolonged freezing. Lab studies show 100% mortality after seven days at roughly 25°F, and they aren’t expected to survive north of regions where January temperatures drop below about 10°F. European fire ants are a completely different species adapted to northern climates. They evolved in cooler parts of Europe and overwinter successfully in Maine’s soil, where insulation from snow cover and deeper nesting protect them from the worst cold. Their cold tolerance is why they’ve thrived along the coast and are now pushing into central Maine.
What Their Stings Feel Like
European fire ants sting aggressively when their nest is disturbed, and because nests are hidden under everyday yard debris, people often step on them barefoot or kneel into them while gardening. A fire ant grips your skin with its jaws, then curves its body to inject venom with a stinger. A single ant can sting multiple times in a circular pattern, delivering seven or eight stings at once.
The initial sensation is a sharp burning. Within about an hour, itchy bumps or welts appear, usually in a circular or semicircular pattern. These last several hours before turning into blisters. By the next day, the blisters fill with white or yellowish fluid. They’re intensely itchy but typically resolve within seven to ten days. Sometimes a single sting causes swelling across a larger area, like an entire lower leg from one sting on the calf. This type of localized reaction usually fades within a couple of days.
Severe allergic reactions are rare, occurring in about 2% of stings. Signs include stomach cramps, nausea, a swollen tongue, or difficulty breathing. Anaphylaxis, which involves a dangerous drop in blood pressure and possible loss of consciousness, is possible but uncommon.
Treating Stings at Home
If you’re stung, brush or slap the ants off quickly since they’ll keep stinging as long as they’re on you. Wash the area with soap and cold water. A cold pack helps with pain and swelling. An over-the-counter antihistamine can reduce itching, and applying hydrocortisone cream twice a day helps with both the itch and the rash. Resist the urge to pop the blisters, as broken skin increases infection risk.
How to Tell Them Apart From Native Ants
Maine has many native ant species, and most are harmless. The key difference with European fire ants is behavior: if small reddish ants swarm aggressively and sting when you disturb a rock, a pile of leaves, or a patch of mulch, you’re likely dealing with European fire ants. Native ants in Maine generally scatter rather than attack. European fire ants also tend to form dense colonies with enormous numbers concentrated in small areas, far more ants per square foot than you’d see with native species. If you can collect a sample (a few ants in a sealed container), the University of Maine Cooperative Extension’s Diagnostic and Research Laboratory can confirm identification. You can reach them at 207-581-3188.
Controlling European Fire Ants in Your Yard
Start with habitat modification. Remove stones, boards, logs, leaf piles, and other ground debris where colonies nest. These ants need moisture, so reducing irrigation and increasing sun exposure by mowing tall grass and pruning dense shrubs makes your yard less attractive to them. This alone won’t eliminate an established population, but it reduces the number of nesting sites.
For actual suppression, bait-based pesticides are the most effective option. Unlike sprays that kill only the ants you can see, baits are carried back to the nest and fed to queens and developing ants, collapsing the colony from the inside. University of Maine research found that broadcasting granular baits directly onto the ground with a handheld seed spreader works significantly better than using bait stations. Most granular products should be applied no more than once every four weeks.
In areas where children and pets play, or near wetlands where runoff is a concern, bait stations are a safer alternative. Liquid baits work better than granular baits in stations, though they need to be refilled when depleted or contaminated. Either way, bait-based control is slow. Expect to wait several weeks before seeing results, and multiple applications over a season are typically needed.
Keep granular bait off paved surfaces where rain could wash it into waterways, and don’t apply it to vegetable gardens. Always follow the product label for application rates.
Preventing New Infestations
European fire ants spread primarily through the movement of soil, plants, mulch, and compost. If you’re bringing any of these materials onto your property, especially from coastal areas of Maine, inspect them carefully before placing them in your yard. Colonies hide easily in potted plants, wood chips, and soil deliveries. If your property is currently free of European fire ants, this inspection step is the single most important thing you can do to keep it that way.