A firefly nearly 100 million years old has been found in amber

The discovery helps us understand when these insects developed their most famous feature - the ability to glow in the dark.

Details

The new species has been named Cretoluciola birmana. It was found in Burmese amber formed in the middle of the Cretaceous period, when dinosaurs still lived on Earth.

The insect was very small - just a few millimetres long. But it was preserved well enough for researchers to see important details of its structure: large eyes, antennae, abdominal segments and a light organ.

It was the light organ that was the key part of the discovery. In the male found, it was bipartite - like many modern fireflies in the Luciolinae group. This suggests that the luminescence system in such insects was already well developed almost 100 million years ago.

To verify the findings, the scientists compared the ancient beetle with modern fireflies. They studied more than 400 features of the body structure and used data on currently living species. As a result, the researchers concluded that they were looking at a real representative of the firefly lineage, not just a similar beetle.

Why it matters

The early history of fireflies has long remained unclear. Similar insects have been found in amber before, but it wasn't always clear whether they actually belonged to true fireflies.

The new discovery provides more reliable evidence: fireflies with developed glow organs existed already in the age of the dinosaurs.

Modern fireflies use light to communicate, attract mates and possibly to defend themselves against predators. Scientists cannot say exactly how Cretoluciola birmana glowed or whether it blinked in the same way as modern species. But its anatomy shows that the "light system" itself was already formed.

This means that bioluminescence in fireflies appeared a very long time ago and turned out to be such a successful evolutionary decision that it was preserved for tens of millions of years.

Background

Amber is often referred to as nature's time capsule. The resin of ancient trees could quickly capture small insects and preserve them with amazing accuracy: with legs, antennae, eyes and other fine details.

For the study of ancient insects, such finds are especially important. Ordinary fossils rarely preserve such fine structures, and amber allows us to view the organism almost as it was when it was alive.

In the case of the ancient firefly, this preservation helped us see the main thing - the glow organ, which links the find to modern fireflies.

Source

A study by Shuailong Yuan and co-authors A true Luciolinae fossil from the mid-Cretaceous Burmese amber provides new insights into the early evolution of fireflies (Coleoptera: Lampyridae) published in Proceedings of the Royal Society B: Biological Sciences in 2026. The scientists described a new species of Cretoluciola birmana from Burmese amber with an age of about 98-99 million years and showed that representatives of the Luciolinae lineage already had luminescent organs in the middle of the Cretaceous.