Crematogaster spp. Lund, 1831

Acrobat ant

The ant that does a handstand, raising its heart-shaped abdomen overhead when alarmed.

Order: Hymenoptera
Family: Formicidae
Group: Ants
Ontario status: Native, established provincewide

Why it matters

Excavates damp wood and insulation, causing moderate structural damage over time. Often mistaken for carpenter ants, which changes the expected damage pattern.

Origin

Native to North American woodlands; several Crematogaster species occur in Ontario.

Behavior

When disturbed, workers raise their heart-shaped abdomen over their head like an acrobat, the source of the name. Forages in trails, day and night.

Living conditions

Nests in moist or decayed wood, tree cavities, stumps, and in houses: damp window frames, eaves and foam insulation. Likes the same damp wood as carpenter ants.

Signs of presence

Small dark ants with heart-shaped abdomens, often near damp wood
Fine frass near nest sites (smaller-grained than carpenter ant frass)
Ants 'doing handstands' when disturbed

Weaknesses

Needs damp or decayed wood, dry structures resist it
Nests are noisy to find: workers are conspicuous when disturbed
Galleries are smaller and shallower than carpenter ant damage

Myths and facts

Myth All big wood-nesting ants are carpenter ants.
Reality Acrobat ants also nest in wood but are smaller, with a heart-shaped gaster, and their control considerations differ.

Research notes

Morphology

Workers 2.5-4 mm, dark brown to black. Gaster heart-shaped, attached dorsally to the postpetiole and carried raised when alarmed. Two-segmented waist; 11-segmented antennae with 3-segmented club.

Diagnostics

Confirm by the heart-shaped gaster + raised-abdomen alarm posture + nesting in moist wood or insulation.

Easily confused with

Carpenter ant, Camponotus pennsylvanicus Carpenter ants are much larger (6-13 mm) with a single waist node and rounded thorax; acrobat ants are small with two waist segments and a heart-shaped gaster.

Life cycle

Adult: Workers live several months; colonies perennial.
Egg: Eggs hatch in ~2-3 weeks at warm temperatures.
Egg to adult: ~6-8 weeks at warm temperatures
Generations per year: Continuous brood in season
Nymph or larva: Legless larvae; naked pupae.

Development

Complete metamorphosis: egg → larva → pupa → adult.

Reproduction

Multiple queens possible; colonies moderate (thousands of workers).

Distribution

Global: Worldwide genus; Ontario species native
Native range: North America (varies by species)
Ontario: Native; established provincewide

Ecology

Arboreal and wood-nesting; excavates galleries in moist/decayed wood and foam insulation. Omnivorous; tends honeydew-producing insects. Defensive gaster-flagging with repellent secretions.

Resistance

No published data.

IPM implications

Moisture-damaged wood is the common denominator, inspection should target the same damp-wood sites as carpenter ant work, but expect smaller, shallower galleries and foam-insulation nesting. The alarm posture makes workers conspicuous during inspection, aiding nest location.

Chemical ecology

Dufour's gland secretions used defensively during gaster-flagging; trail pheromones guide foraging.

Genetics and DNA

No reference genome for Ontario Crematogaster species published as of 2026.

Taxonomy

Order Hymenoptera, family Formicidae, subfamily Myrmicinae, genus Crematogaster. Multiple species in Ontario; treated here at genus level.

Open questions

Species-level identification of Ontario structural records; insulation-nesting frequency in modern construction.

References

Hölldobler, B. & Wilson, E.O. 1990, The Ants, Harvard University Press
Mallis Handbook of Pest Control