Allegheny Mound Ant

Reddish-orange head and thorax with a sharply contrasting black gaster, 3–6 mm. Single petiole node. Mounds are unmistakable, large, conical to dome-shaped, often 1–3 ft tall, surrounded by a 40–50 ft ring of dead saplings and shrubs that the ants have killed by spraying formic acid into the cambium.

Polygyne supercolonies, a single colony may span dozens of interconnected mounds. New mounds bud from existing ones. Aggressive defenders; disturbing a mound triggers thousands of workers spraying formic acid and biting. Sustains itself largely on aphid honeydew from surrounding vegetation it permits to live.

Significant problem in Christmas tree farms, orchards, and ornamental nurseries, where ringed kill-zones destroy plantings. Cosmetic problem on rural lawns and pastureland. Predatory benefit to insect populations is real but rarely outweighs damage in cultivated settings.

Drench individual mounds with a contact insecticide; granular baits are less effective because this species is heavily predatory and only modestly bait-responsive. Treat in early morning or evening when ants are inside the mound.

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