Scientists have uncovered a fascinating survival strategy used by certain caterpillars — producing a rare rhythmic vibration to convince ants to carry them into their nests for food and protection.
The research, published in the Annals of the New York Academy of Sciences, reveals that these caterpillars generate a complex beat known as “double meter”, a rhythm previously identified only in a few primate species.
A secret knock into the nest
The study was co-authored by Chiara De Gregorio, an animal behaviour researcher at University of Warwick. While she typically studies primates, her interest in rhythm and communication led her to examine how caterpillars interact with ants.
Field research in northern Italy involved collecting ant nests and caterpillars from nine butterfly species. Some of these species rely entirely on ants for survival, while others are independent.
Acoustic analysis revealed that all studied insects produced a steady rhythmic pulse known as isochrony. However, caterpillars dependent on ants — and the ants themselves — also generated the far rarer double meter rhythm, where one beat is either twice or half as long as the next.
Rare rhythm in the animal world
Double meter has so far been documented only in a couple of primate species, making its presence in insects particularly striking. Researchers believe this rhythmic matching may function like a “secret knock”, signalling ants to retrieve and protect the caterpillars.
Scientists now hope to conduct further experiments to understand how ants respond when caterpillar rhythms are altered.
The findings highlight the surprising complexity of insect communication and underscore how rhythm plays a role across diverse species.
As researchers note, evolution often produces unexpected solutions — and in this case, survival depends on keeping perfect time.