Invertebrates
Pharaoh Ant
Monomorium pharaonis
Behind a hospital kitchen’s tiled wall, a thin line of pharaoh ants, each smaller than a grain of rice, marches towards a spilled drop of syrup.
Overview
The pharaoh ant, Monomorium pharaonis, is a Not Evaluated ant best known as a pest of heated buildings around the world. Its many-queened colonies, budding nests, and trail signals, including a repellent one, make it one of the most successful and hardest to control of all house-invading ants.
An ant with a “no entry” sign
Pharaoh ants mark good routes with attractive trails and dead-ends with a repellent signal, which saves foragers from wasting time on routes that lead nowhere.
Status
Not Evaluated globally, and best known as an introduced pest.
Pharaoh Ant: common questions
Why is the pharaoh ant so hard to get rid of?
Spraying with insecticide can scatter a colony into many new nests, and its many queens let colonies split and spread.
What is the pharaoh ant's "do not enter" signal?
It leaves a repellent chemical signal that marks dead-ends and abandoned routes, along with attractive trail markers that guide nestmates to food.
Why is it a problem in hospitals?
It can carry disease-causing bacteria on its body into places where patients are vulnerable.
Where is the pharaoh ant found?
It lives in heated buildings worldwide, and outdoors in tropical regions.