Caterpillars don’t have many defenses against predators, and that reality results in the small insects more often than not becoming dinner for some larger creature. In order to shed light on the likelihood of these small critters being consumed, researchers recently glued a bunch of fake ones to plants in various regions around the globe. The faux caterpillars were made of a soft clay that would reveal bit marks and similar things if disturbed; those marks were analyzed once the faux caterpillars were recovered, helping illuminate the final moments such creatures face.
It was a talk between two researchers who had both previously used clay caterpillars that brought this idea to light: the duo — Oxford’s Eleanor Slade and Swedish University’s Tomas Roslin — realized that caterpillars may be more likely to become lunch in some places than others. Thus a study on predation risk was born, one that involved putting fake caterpillars on different types of plants in various environments.
Overall, the team of researchers glued around 3,000 faux caterpillars to plants in places spanning from Australia all the way up to the Arctic, and the results were interesting. After analyzing the bite marks left in the clay caterpillars, researchers determined that these small creatures are more likely to be eaten at lower elevations than higher ones, and that — perhaps not surprisingly — they’re safer nearer to the poles than the equator.
Though we may imagine that birds and similar large animals would often consume things like caterpillars, the study found that ants and other minuscule predators were largely responsible for the pattern. Speaking about this, Swiss Federal Institute of Technology biologist Will Petry said to NPR: “We’ve known for a really long time that there are more species in the tropics than there are in polar regions. But we don’t have as good of an idea of the geography of interactions between species.”