Argentine Ant

size 2.2 to 2.6 mm long. Antennae has 12 segments with no club. Brown; some light brown. Sparse body hairs and no stinger. 

Nest site/characteristics: colonies live in moist areas near a food source. Colony numbers fluctuate seasonally, ranging from one hundred to several hundred thousand workers and many queens.  Foraging workers follow trails with winged queens sometimes being found among them. Argentine ants live outdoors (preferably) in shallow nests in moist areas, including under boards and stones, and beneath plants and along sidewalks. When outdoor conditions are too wet or too dry, Argentine ants invade buildings by trailing along tree and shrub branches, utility lines and wires. 

Feeding Preference: Prefer sweets such as sugars, fruit juices and plant secretions, but will also forage on proteins (meat, insects, eggs.)

Acrobat Ant

size 1/8 in long. 11 segmented antennae, with 3-segmented club. Color varies from black to red and black. Quick to bite; emits a strong odor when disturbed.

Nest sites/Characteristics: Indoors, nests may be located where water damage has occurred, in decayed or damp wood or inside insulating wall panels and wall voids. Outdoors, they nest under rocks or in logs, firewood or trees where decay allows them to tunnel under bark or into wood. 

Feeding Preference: They eat a wide variety of foods, including sweets and proteins. Workers like sugars from sap-sucking insects. They also prey on winged termites. 

Carpenter Ant

size 1/4 to 1/2 in (workers). Antennae has 12 segments with no club. Black; (other species may be dark brown, dark red or a combination of these colors). Circular ring of hairs at end of abdomen. 

Nest site/characteristics: Moderately sized mature colonies contain more than 3,000 workers with one queen per colony (colonies may contain satellite nests that consist of workers, larvae, and pupae.) Nests usually originate in moist, decayed wood and voids and may later expand into sound wood.  Outside, nests are commonly found in dead or damaged portions of trees, rotting logs and stumps.

Feeding Preference: Feed primarily on insect-produced sugars, plant and fruit juices, and insects. Indoors they feed on food debris, including sweets, eggs, meats, cakes, pet food, and grease. 

Citronella/Large Yellow Ant

size 4 to 4/5 mm long. 12 segmented antennae. Yellow/orange color. Emits citronella or "lemon-like" scent when crushed.

Nests sites/characteristics: Citronella ants nest in the soil. Outdoors, they nest under logs and rocks and landscape timbers. They also nest beside foundations and the inside of crawlspaces. The ants often excavate large amounts of soil as they build their passageways. If the colony is under a concrete slab of a structure, the soil may continue to pile up. These ants swarm nearly any time of the year and swarming may occur inside buildings when colonies are located next to or under the structure.

Feeding preferences: Citronella ants feed on sugars they get from insects that feed on plant roots. Because of this, people seldom see the workers.