A colony of bigheaded ants has workers in two size groups. The larger workers, called major workers, serve as defenders. They have very large heads. This is where bigheaded ants get their name. The smaller workers, called minor workers, are about half as large as the major workers.
There are several species of bigheaded ants. They are found in many parts of the U.S, but they are more common in the warmer areas. Bigheaded ants frequently nest in the soil near homes. They make their nest under logs, stones, and woodpiles. Occasionally they nest under the slab of the house and enter through cracks or expansion joints.
Outdoors, bigheaded ants feed on seeds and insects. The major workers use their large jaws, called mandibles, to crack the seeds. Bigheaded ants also eat honeydew that they gather from aphids.
Some species of bigheaded ants make a sound called stridulation. The workers use the sound to alert other workers when they have found food. The sound summons other workers to help bring the food back to the nest. They also use the sound as a signal when there is danger.
Bigheaded ants often forage into homes and other buildings for food. There are reports of workers trailing from outdoor nests to get food from trays in hallways of hotels. When they enter homes, bigheaded ants seem to prefer foods that are high in protein, like meats and peanut butter.
Preventing these ants from invading starts with an inspection outdoors. Look for openings that the ants could use to enter the home. Make sure exterior doors close tightly. Caulk any openings around doors and windows. Small pieces of plastic screen can help keep bigheaded ants from entering through weep holes in brick exteriors. Be sure to trim tree limbs and shrubs that touch the house.