Fire Ants and Asian Needle Ants

By Environmental Management System

June, 2014

When it comes to ants, you may not know that there are 178 species of ants in North Carolina. Many of them are invasive species, and two of those invasive species can be found on the NIEHS campus: the Fire Ant and the Needle Ant. While both species of ants can be aggressive when they’re disturbed, they attack humans and livestock in different ways. These invasive ants do not fulfill the bio-diverse rolls of the native ants that they displace and alter the natural food chain, impacting native ant’s ability to pollinate plants, disperse seeds, and keep other insects in check.

Fire Ants

Fire Ants first appeared in Alabama in 1930; they are originally native to South America and likely arrived to the United States in the soil used in ships’ ballasts. They have since spread all throughout the south and are currently found in 71 of NC’s 100 counties. Red Fire Ants nest in the ground forming visible mounds in open areas; these ant colonies can have more than half a million insects. The “bite” of a fire ant sting is actually the injection of venom into the skin via their stingers. In addition to humans, fire ants will sting pets and livestock.

Why do fire ants appear to sting all at once?

Fire ants are very sensitive to vibrations, so they tend to sting when their target is moving. If someone jerks their leg when they feel the first fire ant sting, other fire ants will feel that movement and also “bite.” While fire ants use pheromones to elicit some behaviors, it is not likely that they communicate about stings with these communication chemicals.

Asian Needle Ants

The Asian Needle Ant likely arrived in the southeastern United States in 1935. They can be found in both open and forested area, and nest under wood debris (including mulch). Their colonies are much smaller than fire ants, ranging from dozens to thousands of ant; their colonies are flat and do not appear like traditional, mounded ant hills. While Asian Needle Ants are not aggressive like fire ants, if they are threatened, they will sting with venom equivalent to four bee stings. Surprisingly, more people are allergic to Asian Needle Ant venom than to honeybees and other bees. Unlike most ants, Asian Needle Ants cannot climb; if you capture a group of ants in a glass jar, Asian Needle Ants will not be able to climb the sides.

If you’re interested in learning more about the Asian Needle Ant, the Fire Ant, and all of NC’s additional ant species, researchers from NC State have developed a comprehensive website with photos, identification guides, and removal information.