Acrobat ants are a group of ants in the genus Crematogaster, named for their distinctive ability to raise their heart-shaped abdomen over their thorax like an acrobat balancing in midair. These small ants occur in forests, woodlands, and urban landscapes, where they nest in decaying wood, tree cavities, and occasionally structural voids in buildings. Although many species are ecologically beneficial predators and scavengers, acrobat ants can become nuisance pests when they invade homes or damage insulation and wiring.
Taxonomy and Classification
Acrobat ants belong to the order Hymenoptera, family Formicidae, and genus Crematogaster. There are dozens of Crematogaster species worldwide and more than twenty recorded in the United States. Several species, including Crematogaster cerasi, Crematogaster laeviuscula, and Crematogaster ashmeadi, are commonly referred to as acrobat ants. They are closely related to other arboreal and wood-nesting ants but are distinguished by their characteristic gaster shape and behavior.
Physical Description
Acrobat ant workers are small, typically around 2.5–4 mm (about 1/8 inch) in length. Their color ranges from light brown to dark brown or nearly black, and some species may appear bicolored. The most distinctive feature is the heart-shaped gaster (abdomen), which is attached to the thorax by a narrow waist and can be raised above the body when the ant is alarmed or disturbed.
Workers have 11-segmented antennae and a flattened petiole, often with small propodeal spines at the rear of the thorax. Colonies are generally monomorphic, with workers of similar size, though reproductive queens and males are larger and winged during nuptial flights. Like other ants, acrobat ants possess six legs, strong mandibles, and a tough exoskeleton suited to their active foraging and nesting habits.
Distribution and Habitat
Acrobat ants are found across much of North America and in many temperate and tropical regions worldwide. In the United States, different Crematogaster species occur in forests, woodlands, parks, and residential landscapes. Some species, such as Crematogaster ashmeadi, are especially abundant in southeastern pine forests, where they are dominant arboreal ants nesting in tree bark and old insect galleries.
These ants commonly nest in decaying tree stumps, logs, and branches, as well as in hollow stems, under loose bark, and in cavities created by wood-boring insects or termites. Around buildings, they may nest in rotting structural wood, foam insulation, wall voids, window and door frames, or spaces around utility lines, particularly where moisture problems have led to decay.
Behavior and Social Structure
Acrobat ants are social insects that live in colonies containing a queen or queens, workers, and developing brood (eggs, larvae, pupae). Colonies often occupy interconnected galleries within wood or bark and may extend through branches or structural elements. When disturbed, workers rapidly raise their gasters over their bodies and may release defensive chemicals, a behavior that inspired their common name.
These ants frequently exploit pre-existing cavities rather than excavating solid wood, taking over old galleries made by carpenter ants, termites, or wood-boring beetles. Trail-following behavior allows workers to move efficiently between nest sites and food sources. In some habitats, acrobat ants form large, dominant colonies in tree canopies, playing a significant role in arboreal food webs.
Diet and Foraging
Acrobat ants are omnivorous and opportunistic foragers. Outdoors, they feed on live and dead insects, arthropod eggs, and honeydew produced by aphids and other plant-sucking insects. They often tend aphids, protecting them from predators in exchange for honeydew, which serves as a valuable carbohydrate source.
When they move indoors, acrobat ants may forage for sweets, fats, and proteins, including spilled food, pet food, and other household materials. Foraging trails can extend from outdoor nesting sites into kitchens, bathrooms, and other rooms through cracks, utility penetrations, or gaps around windows and doors.
Interaction with Humans
Acrobat ants can become nuisance pests when they invade homes or commercial buildings. Indoor sightings often involve worker ants trailing along walls, wiring, or plumbing in search of food. Nesting in moist or decayed structural wood may indicate underlying water damage or previous infestations by other wood-destroying organisms.
Although acrobat ants do not usually cause extensive structural damage on their own, they can strip insulation from electrical wiring and may contribute to localized deterioration of already weakened wood. They rarely sting and are not considered medically important, but their presence in large numbers can be bothersome to occupants and may contaminate food or surfaces.
Management and Prevention
Effective management of acrobat ants combines identification, nesting-site correction, and long-term prevention. Inspection should focus on locating nests in decaying wood, tree limbs touching structures, and moisture-damaged areas such as leaky roofs, window frames, decks, or siding. Eliminating excess moisture, repairing leaks, and replacing rotten wood removes many suitable nesting sites.
Trimming tree branches that contact roofs and siding can reduce ant access to buildings. Indoors, sealing cracks, gaps around pipes and wires, and openings around windows and doors helps prevent new foraging trails from forming. In some cases, targeted use of baits, non-repellent insecticides, or professional pest management services may be recommended, especially where colonies are extensive or difficult to access.
Conservation and Research
Most acrobat ant species are common and not of conservation concern. In natural ecosystems, they act as important predators, scavengers, and mutualists with honeydew-producing insects. Research on Crematogaster species explores their dominance in tree canopies, interactions with other ant species, and their roles in forest food webs. In urban and suburban environments, studies focus on their nesting preferences, relationship to structural moisture problems, and best practices for integrated pest management.