Acrobat Ants

Quick Answer: Acrobat ants (Crematogaster spp.) are small ants, about an eighth of an inch long, named for raising a distinctive heart-shaped abdomen up over the body when disturbed. They range from light brown to black and are often bicolored. They nest in moist or previously damaged wood, foam insulation, and outdoors under bark. They’re mostly a nuisance, but because they favor damaged wood, an indoor acrobat ant can be a clue to a hidden moisture or wood-damage problem.

Most important distinction: Acrobat ants don’t initiate wood damage the way carpenter ants do. They move into wood that’s already compromised, so they’re an indicator, not the original cause.

Behavior & Biology

Acrobat ants belong to the genus Crematogaster, a widespread group named for the heart-shaped abdomen that gives them their acrobatic look. When a worker is threatened, it lifts that abdomen up and over the rest of its body, a posture that’s both a defensive display and the single most reliable way to identify the species in the field.

Outdoors, acrobat ants nest under bark, in dead tree limbs, in old logs, and in wood softened by moisture. When they move toward structures, they gravitate to the same conditions: damp framing, wood damaged by a leak, and even foam insulation, which they’ll hollow out to create galleries. They frequently travel along tree branches, utility wires, and pipes that bridge from the yard to the house.

Colonies are moderate in size and tend to relocate readily when disturbed. Workers forage for sweets, proteins, and the honeydew produced by aphids and other insects, which is why you’ll often see them trailing up shrubs and trees. Because their preferred nesting wood is already compromised, an acrobat ant infestation indoors is worth treating as a prompt to check for the underlying moisture source.