Stinging Ants That May Cause Anaphylaxis Spreading in the US—Here's How to Identify Them

Usually, an ant infestation is just an annoying pest problem with an easy fix, but this year, one particular ant poses a much more serious threat and is gaining ground.

The Asian needle ant, which, according to the United States Department of Agriculture (USDA), has been in the southeastern U.S. for about 100 years, can cause anaphylaxis in humans.

The invasive pests are small and shiny, dark brown to black in color, and the tips of their antennae and legs are a lighter orange-brown shade. Because other ant species in the eastern U.S. resemble Asian needle ants, it can be tricky to identify them. They're not aggressive or defensive like fire ants, but they will inflict a venomous sting if trapped inside clothing or beneath your hand.

Their stings can result in anaphylaxis, a life-threatening allergic reaction. Symptoms include swelling of the tongue or throat, constriction of airways, difficulty breathing, wheezing, weak or rapid heart rate, nausea, vomiting, diarrhea, skin reactions like hives or itching, flushed or pale skin, low blood pressure, and dizziness or fainting. If you think you're having an allergic reaction, seek medical attention immediately.

While it's difficult to know who will react adversely to the ant's sting, those with allergic reactions to a yellow jacket or a honeybee, for example, and need to carry an adrenaline autoinjector (like an EpiPen) may be at increased risk of anaphylaxis from Asian needle ant stings.

The pest has been recorded mainly in southeastern states, with the highest concentration in North Carolina, South Carolina, Georgia, and Virginia. Still, entomologists recently documented their spread into New England and the Midwest. These ants are most active in the summer, mainly in July and August.

Asian needle ants live in logs or firewood and can be found under stones and within leaf litter. They can also appear under mulch, pavers, landscape timbers, and other objects. They don't line up in a trail like other ants. Instead, they tend to walk chaotically and are typically alone, which is probably their most identifying trait. They often displace other beneficial ant species, disrupting the area's ecosystem.

To help control their invasion, remove loose logs, firewood, or leaf piles where they can hide, and keep any other wood dry and off the ground.