Changing size and changing enemies: The case of the mopane worm

That there are systematic changes in the body size composition of the predators attacking a particular species of invertebrate as it grows in body size seems intuitively obvious. Nonetheless, such changes have not been well documented. Here we provide an empirical case study, for the mopane worm (the mopane or anomalous emperor moth Imbrasia belina; Saturniidae) and its avian enemies in South Africa. The body masses of the bird species feeding on successive instars were strongly positively correlated with the masses of those instars. Later instars were fed on by birds with a broader range of' body sizes than were earlier instars. Temporal turnover in specific identities of the predators consuming different instars was considerable, resulting potentially in a strong temporal dynamic in the selection pressures faced by mopane worms.