Caterpillars that disguise themselves as ants do so not only with chemical signals, but also with acousto-vibrational signals. By impersonating ants, the caterpillars gain access to care and protection; the ants, meanwhile, benefit from a sugary substance secreted by the caterpillar. The closer the relationship between caterpillar and ant, the more accurately the caterpillars can mimic the rhythm of ants in these signals. This is the conclusion of a British-Polish-Italian research team, writing in Annals of the New York Academy of Sciences on 25 February.
Caterpillars and ants produce acousto-vibrational signals by tapping or rubbing body parts – such as mandibles – against each other or against a substrate. Recordings of two ant species and nine butterfly species in northern Italy now show that they produce comparable rhythms when doing so. Species with the closest mutual relationships show, for example, similar pauses, or employ the same pattern of long and short intervals.