Ants

Ants are social insects that live in colonies built around one or more egg-laying queens, with sterile female workers doing all the foraging, nest building and defense. In US homes they are mostly a nuisance that follows food and water indoors; the exceptions are carpenter ants, which hollow out wood, and fire ants, which sting.

This page is the overview: how ants live, what they eat, and why that matters when you're trying to get rid of them. For hands-on control go straight to how to get rid of ants; to name the ant on your counter, see types of ants.

How to recognize an ant

• Three body sections: head, thorax, and abdomen (gaster).
• Pinched waist with one or two small nodes (the petiole), clearly visible from the side.
• Elbowed antennae, bent like a knee.
• Six legs. How many legs do ants have? Six, always, attached to the thorax.
• Winged forms (swarmers) have two pairs of wings, the front pair much longer than the hind pair.

These traits separate ants from termites, which have a thick waist, straight beaded antennae and four equal wings. If you saw winged insects coming out of a wall, read termites vs ants before anything else.

How an ant colony works

Every colony has the same castes:

• Queens lay all the eggs. Some species (carpenter ants, most fire ants in single-queen form) have one; others, like Argentine, pharaoh and odorous house ants, have many queens and can split into new nests by "budding."
• Workers are sterile females. The ones you see on the counter are foragers, often 10% or less of the colony. The rest stay home tending brood.
• Males appear only to mate during swarms and die soon after.
• Brood: eggs, larvae and pupae. Larvae are the colony's stomach; they digest protein and pass food back to workers.

This structure explains the most important rule of ant control: killing the ants you see barely dents the colony. The queens and brood are hidden in a wall void, under a slab or in a lawn. Only something the foragers carry home, a bait, reaches them.

Queen ants

A queen starts a colony after a mating flight: she sheds her wings, digs in, and raises her first workers on her own body reserves. Mature colonies of many species then produce new winged queens once a year. Queens are noticeably larger than workers and have a bulky thorax where the wing muscles were. Seeing a lone wingless queen indoors in spring is common and not a sign of an established nest; seeing many swarmers come out of one spot is.

What do ants eat?

Ants need two kinds of food:

• Carbohydrates for workers' energy: honeydew from aphids, scales and mealybugs (the single biggest ant food outdoors), nectar, ripe fruit, sugar, syrup, soda.
• Protein and fat for larvae and egg-laying queens: insects, seeds, meat scraps, grease, pet food.

A colony's preference shifts with the season and with how much brood it is raising (UF/IFAS notes this for crazy ants and other house species). In spring, when queens lay heavily, protein baits may outperform sweet ones; in summer many species switch to sugar. That's why a bait that "stopped working" often just needs to be swapped for a different food type.

Harvester ants in the West collect seeds; leafcutter ants in Texas and Louisiana farm a fungus on cut leaves. Carpenter ants do not eat wood; they excavate it for nest space and eat honeydew and insects.

Do ants sleep?

They do, in short bursts. In a 2009 study of fire ants in observation nests (Cassill and colleagues, Journal of Insect Behavior), workers averaged about 253 sleep episodes a day of roughly 1.1 minutes each, about 4.8 hours in total. Queens slept far longer: about 92 episodes of around 6 minutes, roughly 9.4 hours a day, often huddled together. Sleeping ants folded their antennae and ignored nestmates touching them, and activity didn't follow day and night at all.

Because workers stagger their naps, about 80% of the workforce was busy at any given moment. That's why you can see a trail at 2 a.m. Carpenter ants in particular forage mostly at night; UF/IFAS reports Florida carpenter ant activity peaks from just before sunset to about two hours after.

How long do ants live?

• Workers: a few weeks to a few months for most small house ants; up to a year or more for carpenter ant workers.
• Queens: the long-lived caste. Queens of single-queen species such as carpenter and field ants commonly live 10 years or more, and some lab-kept queens have passed 20. A classic 1997 Nature study by Keller and Genoud linked this to colony life: social insect queens live around 100 times longer than solitary insects, and queens in single-queen colonies outlive those in multi-queen species (like pharaoh and Argentine ants), whose queens are short-lived but constantly replaced.
• Males: days to weeks.

A colony outlives any individual worker, so waiting for the ants "to die off" doesn't work while the queen is healthy.

Ants that matter in US homes

Learn to tell them apart in our types of ants guide, and check what happens when they bite in do ants bite.

Asian needle ants

The Asian needle ant (Brachyponera chinensis) deserves its own note because it stings and is spreading. NC State Extension describes workers as about 5–6.5 mm (roughly 1/5 inch), slender, dark brown to black with lighter orange-brown legs and mandibles, and lists records from North Carolina to Florida and Alabama and north to Virginia, Connecticut and New York. They nest in damp places: rotting logs, leaf litter, under rocks and landscape timbers, around sprinkler heads. They mostly hunt termites, rarely trail into kitchens, and only sting when pressed, usually when someone reaches into mulch or a log pile barehanded. NC State notes the sting is somewhat more likely than a honey bee's to trigger an allergic reaction, so gardeners in the Southeast should wear gloves when moving mulch and logs.

What people who deal with ants say

Pest pros on r/pestcontrol repeat a few points so often they're worth knowing even if you only came here for biology:

• "Sugar ant" is not an ID. The first question pros ask is which ant it is, because bait choice and the chance of colonies splitting depend on species.
• More ants at a bait is good news. Homeowners panic when a bait station draws a crowd; pros say leave it, since foragers are recruiting nestmates to the food.
• Ants in winter mean they live inside. When ants show up indoors during weeks of freezing weather, the colony is in the structure, often in a wall or under a floor, not outside.
• The yard feeds the house. Aphid-covered shrubs, a tree touching the roof or a stump near the foundation keep restocking indoor trails.

What eats ants?

Flickers and other birds, toads, lizards, horned lizards (which specialize on harvester ants), spiders, antlions, armadillos, and other ants. Ant colonies also fight each other for territory. Broad insecticide sprays on lawns kill these predators and competitors along with the ants, which is one reason ants often rebound faster than anything else after a blanket spray. The EPA's integrated pest management approach, targeted baits plus sanitation and exclusion, avoids that.

Are ants beneficial?

Outdoors, yes. Ants aerate soil, disperse seeds, eat fleas, termites and fly larvae, and clean up dead insects. The goal is to keep them out of the house, not to wipe out every ant in the yard. The exception is fire ants near play areas and walkways.

Why ants come inside

Ants enter for food, water, and shelter. Common triggers:

• Rain or drought drives foraging colonies indoors; many people notice ants right after a heavy rain.
• Honeydew-producing pests on foundation plants put trails right against your walls.
• Leaks under sinks and around tubs provide water and, for carpenter ants, soft wood.
• Crumbs, grease and pet food keep them coming back.

When to call a professional

• You see large black ants indoors repeatedly, especially in late winter or spring, or find sawdust-like debris (possible carpenter ant nest in the structure).
• Pharaoh ants in a multi-unit building, where individual treatments keep failing.
• Fire ant mounds in a yard used by small children or someone with a sting allergy, if you'd rather not handle it yourself.
• Three to four weeks of correctly placed baits haven't reduced the trails.

Typical one-time ant treatment costs roughly $150–$300 in the US (approximate; carpenter ant work is often more). See ant control services for what pros actually do.