How do ants find their way by smell?

Have you ever watched ants walking in a winding line beside a picnic? They seem to know which way to go, even without any arrows. How do ants find their way by smell?

The journey starts with an ant searching for food. She walks around until she discovers something her nestmates can eat, perhaps a crumb. That gives her something worth leading other ants toward.

On her way home, the ant leaves pheromones, tiny smell messages, on the ground. These messages mark a path that her nestmates can follow.

Near the nest, another ant meets the smell trail. She detects the pheromones with her two feelers, which stretch out from her head. Those feelers help her find the messages close to the ground.

The following ant moves her feelers from side to side. She checks where the trail smells stronger. Comparing the smell on each side helps her work out which way the path runs.

Ahead, the smell trail curves around a pebble. Can you guess which way the ant will turn if her left feeler finds more of the trail's smell? The crumb still lies out of sight.

She turns left, toward the stronger trail smell. As the path bends, she keeps checking and turning. These small changes help her stay on the winding route instead of wandering away.

Following that route brings the ant to the crumb. The smell trail has guided her to food she could not see from the nest. Now she can collect a piece to carry home.

On the return journey, the ant adds her own pheromones along the path. She makes the same smell trail stronger, rather than making a different route. That helps the next nestmates follow it.

A stronger trail can draw more ants toward the food. As more nestmates choose that route, a busy line forms. Each ant follows smell messages, not a set of visible arrows.

Pheromones. Ants find their way along trails because other ants leave pheromones, which they detect with their feelers and follow.

Next time you see a winding line of ants, you can remember the tiny smell messages guiding their steps.