The pharaoh ant, Monomorium pharaonis, is found worldwide.
How did the pharaoh ant get its name?
They are named after the plagues of Egypt. Found in the book of Exodus ten plagues were inflicted on the pharaoh of Egypt to make him release the Israelites from slavery. These plagues included many insect pests. As these ants have a propensity for invading buildings they are regarded as a plague by many.
Do pharaoh ants have multiple queens?
Known as polygynous each pharaoh ant colony will have many queens. On average about 5% of a colony may be made up of queen ants. This allows them to easily break away and form new colonies and makes them less dependent on the survival of one queen. Each year a sub-set of a colony will leave to establish a new independent colony. Pharaoh ants can also join or work for other pharaoh ant colonies without facing any hostility.
How big are pharaoh ants?
Measuring only 1.5 mm (1/16 inch) in length these ants are small. The queens are about 3 times bigger than the worker ants measuring about 5mm.
How do pharaoh ants use pheromones to communicate food sources?
They leave negative pheromone trails to mark areas with no food. Notably, pharaoh ants are unusual in that they leave negative pheromone trails to communicate that they have checked out an area for food and not found anything of value. This means that other ants do not waste time searching areas already explored. The negative pheromone signal lasts for about 2 hours. This makes the pharaoh ant colony extremely efficient at finding food sources.
As with many species, they also leave positive pheromone trails. If one ant finds a good food source they will mark its source back to the colony with a powerful pheromone trail. That is why you will see a long trail of these ants in buildings all gathering at one food source.
How do pharaoh ants locate new food sources?
They use scouts to locate food sources. Pharaoh ants are not active at night but each morning an advanced scout party is sent out to search for food sources. All the while they will be releasing positive and negative pheromones to guide the majority of ants to areas with the densest resource value. If a food source is left out in a building the scouts will likely find it and it won’t be long before hundreds of more ants are on the scene.
How do pharaoh ants secure long term food stores?
They have a special caste whose job is to eat food. This special ant has quite a role. If there is excess food then rather than let it go to waste this caste known as gasters will eat up the excess food. They have the ability to store this energy and regurgitate the sugary food when food supplies dwindle. This works as a backup or insurance policy to make sure the queens never run out of food.
Do pharaoh ants spread disease within their colonies?
They always wash before entering their nest. Pharaoh ants would appear to be very hygienic. This washing behavior may well help to ward off the risk of spreading disease within the colony. They have specially designed bristles on their legs which act as a brush to wipe away dirt particles. (Source)
Do pharaoh ants nest in buildings?
They are often found in buildings. These ants can propagate very quickly and food sources within a building can attract them to establish themselves in these areas. Because they can move between colonies and sections of a colony split to form new colonies they are very difficult to control. In fact, attempts to kill them can actually encourage the colony to split resulting in greater numbers, this is known as budding.