Deciphering the aromatic world of ants

Ants live in well ordered groups and work hard. They release chemicals that give them a particular smell. Those chemicals help researchers learn how ants act and how they deal with the world around them.

Each ant starts as an egg laid by the queen. It passes through worm like larval stages - emerges as an adult with a set job. Worker ants leave the nest to gather food, repair the nest and feed the young. The queen stays inside and lays eggs. Workers live for weeks or months - a queen lives for years.

The colony survives only if workers find food. They lay down scent trails made of pheromones that guide nestmates to the food and back. The trail lets hundreds of ants cover large areas quickly. Different species eat different foods - some eat plants, others eat insects - depending on where they live.

Food is not eaten at once. Workers store part of it in underground rooms. Some species grow fungus gardens and eat the crop. Others guard aphids and collect the sweet liquid the aphids release. Ants pass food mouth-to-mouth in a process called trophallaxis - this habit moves nutrients through the colony and keeps the group united.

Ants possess body parts and habits that let them exploit many kinds of food. Some species strike deals with plants or with other insects so they gain steady nourishment. Their ability to switch foods helps them endure shifts in weather or landscape.

Chemical signals sit at the heart of those feats. Pheromones warn of danger, mark a food site or announce that a queen is ready to mate. One major chemical is formic acid, the same substance that gives ants their sharp, vinegar like odor. The acid also repels enemies and doubles as a trail marker.

A second set of smells comes from hydrocarbons - long molecules that coat the outer shell of each ant. Those molecules carry a scent badge that nestmates recognize - ants know who belongs to the home colony. The exact mix of hydrocarbons differs from species to species and even between castes within one nest.

Outside factors also tweak the odor. The food the ants eat, the soil they live in and the microbes they contact all alter the chemical blend - two groups of the same species sometimes smell different.

People detect the ant smell in different ways. Some note a sharp biting odor - others smell nothing. The variation shows how complex the chemical messages are and how personal the human nose behaves.

Inside an ant colony, scent rules daily life. Formic acid and body-coating hydrocarbons guide foragers, bind nestmates together and keep the entire society alive.