Do Glow‐Worm Larvae (Coleoptera: Lampyridae) Use Warning Coloration?

Abstract

It is generally believed that the glowing behaviour of lampyrid larvae may be an aposematic display. Moreover, larvae of the common glow‐worm (Lampyris noctiluca) show at least two other features, which can be used in aposematic strategies. The first is their suggestive colour pattern of yellow‐pinkish lateral dots on a jet‐black background and the second a possible warning odour. We performed experiments with starlings (Sturnus vulgaris) to test, in particular, for the significance of the colour pattern as a warning signal. Learning experiments showed that glow‐worm larvae were distasteful and that starlings showed increasing avoidance of the distasteful prey through a learning process. Experiments with mimics and glow‐worm larvae with obscured colours showed that starlings recognized glow‐worm larvae by their colour pattern. However, there was an important effect of experience as one group of starlings that had previous contact with edible glow‐worm mimics, showed delayed avoidance learning and was able to discriminate mimics from glow‐worms thereafter.