A red and black striped ant is most likely one of three things: a velvet ant (which is actually a wasp), an elongate twig ant, or a red and black carpenter ant. The answer depends on the insect’s size, fuzziness, and where you spotted it. Each of these looks strikingly different up close, and knowing which one you’re dealing with matters because some deliver a seriously painful sting.
Velvet Ants: The Fuzzy “Cow Killer”
If the insect you saw was fuzzy and walking on the ground, you almost certainly spotted a velvet ant. Despite the name, velvet ants are actually wasps in the family Mutillidae. The females are wingless, covered in dense hair, and look remarkably like large, brightly colored ants. The most common species in the eastern United States is Dasymutilla occidentalis, which is black overall with vivid patches of orange-red hair on its midsection and abdomen. Females reach about 3/4 inch long, making them hard to miss.
Males look similar but have wings and cannot sting. The females, however, are the reason velvet ants earned the nickname “cow killer.” Their sting ranks at a level 2 on the Schmidt Sting Pain Index, described by the index’s creator as “instantaneous, like the surprise of being stabbed.” The pain is intense but temporary, and the sting is not dangerous to healthy adults. Velvet ants are solitary and not aggressive. They sting only when stepped on or handled directly.
You’ll typically find velvet ants wandering across sandy soil, open lawns, or bare patches of ground. They’re parasites of ground-nesting bees and wasps, so they don’t build colonies or invade homes. If you see one, it’s simply searching for a host nest. There’s no reason to treat your yard for them.
Elongate Twig Ants: Slender and Wasp-Like
If the insect was slender, not fuzzy, and you found it on a plant or tree, it’s likely the elongate twig ant (Pseudomyrmex gracilis), also called the slender twig ant or Mexican twig ant. These are true ants, about 1/3 inch long, with a distinctly wasp-like build: long body, large eyes, and a narrow waist with two segments.
Their color pattern is what catches people’s attention. In the southeastern United States, they’re typically bicolored with a black head, black abdomen, and a bright orange midsection. That bold contrast isn’t just for show. It likely serves as a warning signal to predators, advertising the ant’s painful sting. And the sting is genuinely unpleasant for an ant this size.
Elongate twig ants nest in small colonies inside hollow twigs, dead branches, and plant stems. They’re found in a wide range of habitats, from rainforests and mangroves to suburban yards with hardwood trees. Because their colonies are small (with a single queen), they rarely become a pest problem. You’re most likely to encounter one while pruning branches or gardening.
Red and Black Carpenter Ants
If the insect was large, smooth (not hairy), and you found it near wood or inside your home, a carpenter ant is the most likely candidate. Several carpenter ant species display red and black coloring. Camponotus vicinus, common in the western United States, is typically red and black. The western black carpenter ant (C. modoc) is mostly black with dark red legs. Workers range from 1/4 to 1/2 inch long, and you can identify them by their single-node waist and smoothly rounded back when viewed from the side.
Carpenter ants are the species most likely to cause problems at home. They don’t eat wood like termites, but they excavate it to build nests, carving out extensive networks of galleries and tunnels. They usually start in areas already damaged by water or decay, then expand into sound wood. Indoors, they nest in wall voids, hollow doors, and insulation. A large colony can compromise structural integrity over time.
The typical setup involves a parent nest outdoors in a live or dead tree, woodpile, or landscaping material, with satellite nests extending into nearby buildings. Some species maintain multiple queens in a single colony. C. vicinus can have as many as 40 queens in one nest, which makes established colonies resilient and harder to eliminate.
How to Tell Them Apart
- Fuzzy and on the ground: Velvet ant. About 3/4 inch, dense orange-red hair, solitary. Not a true ant.
- Slender with large eyes, on plants: Elongate twig ant. About 1/3 inch, bicolored orange and black, wasp-like shape.
- Large and smooth, near wood: Carpenter ant. 1/4 to 1/2 inch, red and black coloring, found in colonies near or inside structures.
The key distinguishing features are texture (fuzzy vs. smooth), body shape (stout vs. slender vs. robust), and location. Velvet ants wander alone across open ground. Twig ants stay on vegetation. Carpenter ants follow trails between their nest and food sources, often along baseboards, window frames, or tree branches touching your house.
Sting First Aid
All three of these insects can sting, though carpenter ants are far less painful than the other two. If you’re stung, wash the area with soap and water and apply a cold compress to reduce swelling. Resist the urge to pop any blister that forms, since breaking the skin open invites infection.
Most stings resolve on their own within a few hours to a couple of days. Watch for signs of an allergic reaction or infection: fever, chills, difficulty breathing, increasing swelling, or cloudy fluid draining from the sting site. Some people are sensitive to formic acid, which ants inject during a sting, and can have stronger reactions than usual.
Managing Carpenter Ants at Home
Velvet ants and twig ants rarely need control measures. Carpenter ants are the exception, since they can damage your home if left unchecked. The first step is finding where they’re nesting. Look for small piles of sawdust-like shavings (called frass) near baseboards, window sills, or wooden beams. Follow ant trails in the evening, when workers are most active, to trace them back to the nest entrance.
Eliminating moisture problems is the single most effective prevention strategy. Fix leaky pipes, improve ventilation in crawl spaces, and replace water-damaged wood. Carpenter ants need moisture to establish nests, so drying out problem areas makes your home a much less attractive target. Trim tree branches and shrubs that touch the house, since these serve as highways from outdoor parent nests to indoor satellites.
For active infestations, bait stations placed along foraging trails can be effective because workers carry the bait back to the nest. The goal is always to kill the queen or queens. Surface sprays kill visible workers but rarely reach the colony’s core. If you’re finding carpenter ants repeatedly inside your walls or hearing faint rustling sounds in wooden structures, a professional inspection can help locate hidden nests that DIY methods might miss.