Colour patterns in Lepidoptera evolved mainly as signals to predators. Heliconius are indeed Müllerian mimics. Reply to Mouy (2022).

A recent paper in the journal Evolutionary Ecology by Henri Mouy, an independent researcher and theoretician who gives his address as “City of Westminster, London, UK,” argues that aposematism (warning colour) and Müllerian mimicry are problematic hypotheses. Instead, he claims that the bright colours and apparent colour pattern mimicry act primarily as an intraspecific or interspecific communication device to enable aggregation. In this critique, I show that the long-standing understanding that aposematic and mimetic colour patterns communicate directly with predators is much more likely than Mouy’s aggregation hypothesis.