Argentine Ant: (Linepithema humile)

• 1/8 inch (3.5 mm) long
• One node segment with sharp, pointed peak
• Brown; some light brown
• Uneven thorax
• 12-segmented antennae, no club
• Sparse body hairs
• No stinger

Nest site/characteristics: Argentine ant 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; winged queens can sometimes be found among them. Argentine ants live outdoors in shallow nests in moist areas, including under boards and stones, beneath plants and along sidewalks. Argentine ants also will nest indoors. 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 Preferences: Argentine ants prefer sweets such as honeydew, fruit juices and plant secretions, but will also forage on proteins (meat, insects, eggs) and fats and even attack small, vulnerable animals.

Carpenter Ant: (Camponotus pennsylvanicus)

• 1/4-1/2 inch (7-13 mm) long
• Black (other Camponotus species may be dark brown, dark red or a combination of these colors)
• One node segment
• Spineless thorax, profile evenly rounded on upper side
• Circular ring of hairs at end of abdomen (visible with hand lens)
• Top of gaster covered with long, pale yellow or white hairs
• 12-segmented antennae, no club
• No stinger

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; together with the main colony, the total population may exceed 15,000). Nests usually originate in moist, decayed wood and voids and may later expand into sound wood. Look for coarse sawdust piles (frass) that contain insect body parts and listen for the sound produced as workers chew to remove wood to enlarge the nest. Outside, nests are commonly found in dead or damaged portions of trees, rotting logs and stumps.

Carpenter ants forage alone or along trails 300 or more feet from the nest. “Trunk trails” between parent and satellite nests are clear of vegetation and debris, typically cutting across lawns. Carpenter ants enter buildings around door and window frames, through eaves, along plumbing and utility lines, and over branches touching the structure. Peak foraging occurs at night.

Feeding Preferences: Carpenter ants feed primarily on insect honeydew, plant and fruit juices and insects. Indoors, they feed on food debris, including sweets, eggs, meats, cakes, pet foods, and grease.

Pavement Ant: (Tetramorium caespitum)

• 1/8 inch (3.5 mm) long
• Light brown to black with paler legs and antennae
• Two node segments
• Uneven thorax has pair of small spines on upper back
• 12 segmented antennae, 3 segmented club
• Head and thorax grooved or sculpted with characteristic parallel lines on workers and swarmers
• Stinger present, but rarely used

Nest site/characteristics: Colonies average 3,000-4,000 ants with several queens. Pavement ants normally nest in soil, however, they occasionally nest indoors in walls, insulation and under floors. Colonies will move near a heat source in winter. Pavement ants often follow pipes through slabs to access buildings. Outdoors, these ants nest in soil under stones, slabs, next to buildings and in pavement cracks. They enter through cracks in slabs, expansion joints and natural openings of buildings. Pavement ants like to travel under the edges of carpet next to the tack strip.

Feeding Preferences: Pavement ants are opportunistic feeders that will “swarm” on foods that appear within their foraging range. Indoors, pavement ants feed on meats, nuts, cheese, honey, bread crumbs and grease. Pet food bowls are common foraging sites for pavement ants. Outdoors, this ant feeds on insects, honeydew, seeds and plant sap.

Pharaoh Ant: (Monomorium pharaonis)

• 1/16-1/12 inch (2.0-2.1 mm) long
• Pale yellow to reddish body with black shading on the top, rear portion of he abdomen
• 12 segmented antennae, 3 segmented club (as opposed to 10 segmented antennae, 2-segmented club for the thief ant)
• Two node segments
• Uneven thorax with no spines
• Stinger present, but rarely extended and visible

Nest site/characteristics: Pharaoh ant colonies range in size from several hundred thousand workers and several hundred reproductive females to very small colonies with 100 workers and one or two females. These ants nest almost anywhere, but prefer warm, humid areas near sources of food and water-in wall voids, behind baseboards, in furniture, under floors and between linens. In southern regions, colonies can exist outdoors. Workers range widely from the nest and establish visible trails to food and water sources. Pharaoh ants commonly use electrical and telephone wires, plumbing and other utility lines as trail routes. Outdoor, these ants nest in debris collected on flat roofs, entering and exiting via poorly caulked or defective windows, under flashing and through weep holes.

Feeding Preferences: Pharaoh ants have a wide preference of foods, from syrups to fruits, sweets, meats, pet foods and dead insects. Pharaoh ants have a high daily water requirement. Workers forage for water just as aggressively as for food. They will “harvest” water from unusual sources, such as aquariums, pet dishes, condensation on plumbing fixtures and windows, refrigerator condensation pans, air conditioners and house plants. In health care facilities, Pharaoh ants have been known to forage on the wounds of immobile patients or residents.