BUTTERFLY WING MARKINGS ARE MORE ADVANTAGEOUS DURING HANDLING THAN DURING THE INITIAL STRIKE OF AN AVIAN PREDATOR.

The "false head" hypothesis states that due to the posterior ventral wing markings of certain butterflies which resemble a "false head," visually hunting predators, such as birds, are deceived into attacking the hind wing area rather than the true head of the butterfly. In the laboratory, six groups of artificially marked dead cabbage butterflies, Pieris rapae, were presented to Blue Jays, Cyanocitta cristata. Of the six "false head" markings, only the eyespot significantly influenced the point of attack. All of the "false head" markings, however, led to a greater proportion of attacks to the hind wing area of the butterfly. In the course of prey handling following an initial attack, each of the six "false head" markings significantly directed predator handling strikes away from the true head of captive butterflies to the anal angle of the hind wing. In a second experiment, live P. rapae with "false head" markings were mishandled and thus escaped, significantly more frequently than controls. Therefore, "false head" markings may confer a selective advantage by increasing the probability of escape, particularly during handling. © 1985 The Society for the Study of Evolution.