Allegheny Mound Ant
(Formica exsectoides)

Size: 6–9 mm
Characteristics: Reddish-brown, aggressive, builds large visible soil mounds
Legs: 6
Antennae: Yes
Wings: Seasonal (reproductive ants only)

Habitat:
These ants prefer open, sunny areas such as lawns, forest edges, and fields, where they
construct massive underground colonies beneath soil mounds. Colonies can span
several feet underground and persist for years if left untreated. Their nests
often expand toward landscaped areas near homes.

Threats & Dangers:
Allegheny mound ants are highly defensive and will bite repeatedly when disturbed. They spray
formic acid, which can cause skin irritation and makes outdoor spaces
uncomfortable or unsafe for pets and children. Large mounds can also damage
turf and landscaping.

Control Measures:
Surface treatments alone are ineffective due to the depth of the colony.
Professional-grade mound and soil treatments are required to penetrate the nest
and eliminate the queen. Ongoing perimeter monitoring prevents reinfestation.