Those Tiny Clay Chimneys in the Amazon Finally Have an Answer

Deep in the Amazon rainforest near Manaus, Brazil, small clay structures poke up from the forest floor like tiny smokestacks — and for years, nobody could say with confidence what they were actually for. Scientists could see them. They could describe them. They just couldn’t explain them.

A peer-reviewed study published on February 23, 2026, finally offered an answer — and it turned out to be surprisingly straightforward. These little mud towers, built by a species of cicada while it is still underground, serve two very practical purposes: they help young cicadas breathe, and they help keep ants away.

It is the kind of discovery that makes you wonder how long nature has been quietly solving problems that we were only just beginning to ask about.

The Tiny Architect Behind the Amazon Clay Chimneys

The towers are built by a species known as Guyalna chlorogena, sometimes called the Amazon “architect cicada.” Like all cicadas, this insect spends its juvenile stage — called the nymph stage — underground. It lives there, develops there, and eventually has to make its way to the surface to complete one of the most dramatic transformations in the insect world: molting.

Molting is the process where the nymph sheds its old skin and emerges as a fully winged adult. It is a remarkable moment, but also a deeply vulnerable one. The insect is exposed at the surface for hours, and it cannot easily dig back down if a predator shows up. That window of exposure is exactly where the clay chimneys come in.

Before climbing out, the nymph constructs these mud towers from the outside, building upward from the soil. The structures look almost whimsical from above — like something a child might press into wet clay — but their function, the new research suggests, is anything but accidental.

What the 2026 Study Actually Found

The research team backed up their conclusions with real field experiments, including tests that pushed the structures to the point of failure. This hands-on approach gave the findings more weight than simple observation alone.

According to the study, the towers serve two confirmed functions:

• Ventilation: The chimney structure helps young cicadas breathe while they are still in the underground nymph stage, improving airflow around the developing insect.
• Ant deterrence: The towers reduce the chances of ants reaching the nymph during its vulnerable period near the surface. Ants are a serious threat to soft-bodied insects during molting, and a physical barrier — even a modest clay one — can make a meaningful difference.

The simplicity of the answer is part of what makes it striking. These are not elaborate structures built for display or temperature regulation or any of the more complex theories that had been floated before. They are, at their core, a breathing tube and a fence.

Why This Discovery Matters Beyond the Amazon

It is easy to read a story like this and think of it as a curious footnote from a distant rainforest. But what the cicada chimney research actually illustrates is something much broader: how much animal behavior — even behavior that has been observed and documented — remains genuinely unexplained.

These towers had been known to scientists for years. They had a name. They were associated with a specific species. And yet the question of why they existed remained open. That gap between observation and understanding is more common in ecology than most people realize, especially in environments as complex and understudied as the Amazon basin.

The fact that a study using relatively direct field experiments — physically testing the towers until they failed — could resolve a long-standing mystery also says something about methodology. Sometimes the most effective science is the most direct.

A Closer Look at the Cicada and Its Construction

The towers have been described as looking like tiny smokestacks rising from the forest floor — an apt image for structures that, it turns out, really do function partly as ventilation shafts.

What Happens During the Molt — and Why the Tower Helps

The molting process itself happens quickly, but the hours surrounding it are among the most dangerous in the cicada’s life. The nymph has to transition from a soil-dwelling juvenile into a winged adult, shedding its entire exoskeleton in the process.

During that time, its body is soft, its wings are not yet functional, and it cannot retreat underground if threatened. Ants, which are abundant on the Amazon forest floor and highly effective at exploiting vulnerable insects, represent a real and consistent danger.

The clay tower addresses both problems at once. It creates a small physical structure that makes ant access harder, and it improves the airflow around the nymph in the hours before and during the molt. Two threats, one structure, built from mud by an insect that has never read a biology textbook.

Frequently Asked Questions

What are the Amazon clay chimneys made of?
They are built from clay and mud by the nymph of the cicada species Guyalna chlorogena while it is still in its underground juvenile stage.

Why do cicadas build these towers?
According to the 2026 study, the towers help young cicadas breathe and reduce their exposure to ant predators during the vulnerable molting period.

Where are these cicada towers found?
They have been documented on the rainforest floor near Manaus in northern Brazil, in the Amazon basin.

How did researchers confirm what the towers are for?
The research team conducted field experiments that included physically pushing the structures to the point of failure, helping them verify the towers’ functional role.

When was the study published?
The peer-reviewed study was published on February 23, 2026.

Had scientists seen these towers before the study?
Yes — the towers had been observed and described by scientists for years, but their exact purpose had not been confirmed until this study provided experimental evidence.