Why do ants walk in a line?
For grown-ups: the science
Ants often walk in lines because they follow smell trails that lead to food and back to their nest.
Many ants lay pheromones, chemical signals that other ants detect mainly with their antennae. Successful routes can be reinforced as more ants add pheromone, helping the colony recruit workers efficiently; trails can fade or change when food is gone or conditions shift.
What about...?
Ask your child's own question
Transcript
Look at those tiny ants marching across the sidewalk. Why do they walk in a line?
An ant that finds food can leave a faint smell on the ground as it walks. This smell helps show other ants the way.
Other ants touch the ground with their feelers and follow that smell. As more ants walk there, the smell trail gets stronger.
The line can lead from the nest to food and back again. It helps the ants find a good path together.
So that's why ants often walk in a line. They are following a smell trail left by other ants.