How do we know?
↻ One of the pages with a moving picture
Scientists counted ants by gathering nearly 500 studies.
- A scout ant finds food.
- On the way home, it leaves a scent trail on the ground, made of chemicals called pheromones.
- Other ants pick the trails that smell strongest, so they all follow the same path.
- Ants also remember the route. With scent on the trail, they walk straighter and faster.
How do you count every ant? Scientists gathered ant counts from nearly 500 studies around the world and used them to estimate the total.
Ants can fix their trails. In Jalisco, Mexico, turtle ants march along branches high in the trees, and fix their trail when a branch breaks.
No ant is in charge. Ants build trails without a plan, using simple rules.
Wow number
20 quadrillion Scientists estimate there are about 20,000,000,000,000,000 ants on Earth. That’s a 20 with 15 zeros!
Myth or fact?
A leader ant plans the trail for everyone. Myth. Ants build trails without a plan, using simple rules.
Ants can repair a broken trail. Fact. Turtle ants find a new path when a branch breaks.
Think about it
What do you think happens to a scent trail after the food is gone?
Where in the world?
Jalisco, Mexico where turtle ants march along branches high in the trees, and fix their trail when a branch breaks — 20.5° N, 103.5° W.
Where these facts come from
Every number on page 68, and who measured it
This page tells us how ants lay scent trails and follow the strongest ones.
Uncovering the complexity of ant foraging trails — A science paper about ant trails, shared by the U.S. National Library of Medicine
pmc.ncbi.nlm.nih.gov/articles/PMC3291321
We checked it on 31 October 2026
This page tells us how scientists estimated the number of ants on Earth.
HKU initiates Global Ant Census — The University of Hong Kong
lead.hku.hk/en/article/2022/09/hku-initiates-global-ant-censusat-least-twenty-quadrillion-ants-dominate-the-global-ecosystems
We checked it on 5 November 2026
This is the science paper with the count of about 20 quadrillion ants.
The abundance, biomass, and distribution of ants on Earth — The science paper that counted the ants on Earth, from the journal PNAS, shared by the U.S. National Library of Medicine
pmc.ncbi.nlm.nih.gov/articles/PMC9546634
We checked it on 31 October 2026
This page tells us how turtle ants in Mexico build and fix their trails.
Stanford University
news.stanford.edu/stories/2017/10/algorithm-ants-create-trail-networks
We checked it on 31 October 2026
Has this changed?
How ants form lines is not going to change.
The number of ants is an estimate, and it may change as scientists count more.
Words from this page
- scout
- An ant that goes out alone to look for food.
- pheromone
- A chemical that an animal gives off, which other animals of its kind can smell.
Try it!
Make a chalk ant trail.
1. Outside, one person is the scout. Hide a “food” toy and walk back, drawing chalk dots. 2. Everyone else follows the dots to the food, one by one, like ants. 3. Rub out a few dots in the middle. Can the line still find its way?
What happens: the line follows the dots, and when some are gone, people search around until they find the trail again.
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