Smedley and colleagues collected the caterpillar secretions and tested them against predatory ants. Ants that contact the secretions reject the caterpillars and engage in “cleaning” behaviors to remove the chemicals. The droplets can be rinsed from the caterpillars by solvent. Droplet removal eliminates much of the deterrent properties of the caterpillar. Ants will eat mealworms, but transferring the mayolines to the mealworms will deter the ants.
Ants can be important biological control agents, keeping pest populations in check. Caterpillars that can deter ants, can minimize mortality due to predation and develop large populations. This is another reason why Cabbage White Butterflies are so numerous.
*Scott R. Smedley, Frank C. Schroeder, Douglas B. Weibel, Jerrold Meinwald, Katie A. Lafleur, J. Alan Renwick, Ronald Rutowski, and Thomas Eisner. Mayolenes: Labile defensive lipids from the glandular hairs of a caterpillar (Pieris rapae). PNAS May 14, 2002 vol. 99 no. 10 6822-6827