Eyespot peek-a-boo: false eyes improve the survival of caterpillars in
leaf rolls
Abstract
Deimatic displays typically involve body parts that can conceal or
reveal visual signals, potentially reducing detectability at a distance
while startling predators up close. Some species may achieve this
“conceal-then-reveal” effect using modified aspects of their
environment (environmental deimatism hypothesis). The larvae of
spicebush swallowtail butterflies (Papilio troilus) possess large
eyespots, and rest in leaf rolls during the day. I tested the hypothesis
that leaf rolls reduce eyespot conspicuousness while maintaining eyespot
effectiveness by comparing avian predation on 659 artificial larvae:
eyespotted and non-eyespotted, presented in leaf rolls or on open
leaves. Leaf rolls reduced predation regardless of color pattern.
Eyespots also reduced predation, but only for artificial larvae in leaf
rolls. On open leaves, eyespots neither increased nor decreased
predation. These results suggest that eyespots and leaf rolls can
combine to create a deimatic display – and that this strategy likely
evolved to enhance existing antipredator effects of leaf rolls.