Why leaves of some trees turn red in autumn is still a conundrum for biologists. One idea is that trees use red to signal they are of inferior quality for aphids migrating to the trees.

However, whether red can indeed by distinguished from green by these herbivores is unclear. We show that red leaf colouration is indeed less attractive to aphids than of green, whereas yellow is much more attractive.

While autumnal red could therefore still be a signal of the tree's quality, it could also serve to mask the over-attractive yellow that is unveiled in senescing leaves.

Proceedings of the Royal Society B: Biological Sciences

Proceedings B
is the Royal Society's flagship biological research journal, dedicated to the rapid publication and broad dissemination of high-quality research papers, reviews and comment and reply papers. The scope of journal is diverse and is especially strong in organismal biology.

Proceedings of the Royal Society B: Biological Sciences