What does it look like?
Big-headed ants are a relatively small ant that are grey-yellow to dark brown in colour and covered in many sparse, long hairs. Big-headed ants have two main growth forms, major workers are usually about 3.5mm long and have very large heart-shaped heads when compared to the minor workers, which are about 2mm long. Major workers mainly remain in the nest and minors do most of the foraging.
Big-headed ants are known primarily from tropical lowland regions, but range into more temperate latitudes, including New Zealand. They tend to be more common in open,disturbed habitats with weedy vegetation but they are also found in coastal habitats, forests (both exotic and native), shrubland, grassland, wetlands and urban and agricultural areas.
Why is it a problem?
Big-headed ants are omnivorous. They feed on invertebrates and small vertebrates (e.g. hatching birds) and also harvest seeds. This has direct and indirect effects on invertebrate communities, vegetation and ecosystem processes. They are aggressive to other ant species and can reach high densities due to a lack of intercolony aggression.