Caterpillar Warning System Also Helps It Disappear

The distinctive orange and black striping of the cinnabar moth caterpillar not only acts as a warning, but helps it disappear from potential predators at a distance, University of Bristol researchers have discovered.

caterpillar
Image credit : James Barnett

The caterpillar, often found in the UK near ragwort, is very visual at close range but when viewed from a distance it’s stripes blend to match its background demonstrating that it has an extra defence against being eaten by birds, wasps and beetles.

University of Bristol PhD student James Barnett examined the caterpillar against its natural background of ragwort plants using UV photography and image analysis.

The study, now published in Royal Society Open Science will add to research on distance-dependent signalling with work now continuing to investigate how changes in habitat, foraging and climate can affect it.

James said: “Bright conspicuous signals are frequently used by defended prey to warn their predators to stay away. But being highly conspicuous increases the likelihood of encountering a predator which is either immune to the defence or naïve to its meaning.  By combining a highly salient warning signal with camouflage, the cinnabar caterpillar gets the best of both worlds, an effective deterrence and a low encounter rate with predators.”

Co-author Innes Cuthill added, ‘Biologists have tended to view camouflage and warning signals as opposites: one minimising conspicuousness and the other maximising it. Jim’s work shows that some creatures manage to combine both defences in the same colour pattern.’

Source : University of Bristol