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Thief Ant

Thief Ant

Often mistaken for pharaoh ants due to similarities in colour and size of the workers, thief ants get their names from their habit of stealing food, larvae, and pupae from neighbouring colonies. They are also called “grease ants” due to their preference for grease as a source of food.


Why should I be concerned?

Thief ants will travel great distances in search of food and are capable of getting into sealed food containers. They resistant to conventional ant traps, and are not attracted to sweets. It is difficult to find these ants and the best method is to follow the trails back to their nesting location. Thief ants also appear to be resistant to most insecticides. Colonies may establish themselves inside a building and go unnoticed for a long period.

Habitat and Behaviour

A day in the life of thief ants

Thief ants can survive just about anywhere. They can live inside people’s homes, in the walls or under the floorboards. when outdoors, they can build nests under rocks and in exposed soil or logs. When all else fails, they can move into another colony. Thief ants often build tunnels that lead to another ant colony for a reliable and steady source of food.

Colonies can have multiple queens and the number of workers can vary from a few hundred to a few thousand depending on the availability of food. Colonies with a reliable source of food require fewer workers. These ants will forage along natural borders such as walls, and utility lines.

Thief ant queens and drones have wings, both of which take part in mating flights. On average, a single queen will lay 100 eggs each day. The eggs will take 52 days to become workers.


  • Yellow to light brown in colour, darker abdomen
  • Workers are 1.3 to 1.8 millimetres, queens are approximately 6 millimetres
  • Three-segmented club on each antenna
  • Thorax is evenly rounded
  • Two segments (nodes) between the thorax and abdomen

Tips for prevention and control

These tips may help you get rid of thief ants in your home:

  • Clean underneath and around appliances to remove grease and debris
  • Limit food preparation and consumption to one or two areas
  • Eliminate entryways by sealing all gaps and cracks in the baseboards, window and door frames
  • Check and repair all pipe and faucet leaks

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