The metalmark butterfly cooperates with ants when it’s a caterpillar, only to stab them in the back when it has metamorphosed into a beautiful – thieving – butterfly.
While still a caterpillar, the metalmark butterfly wins over local ants, including those of the species Ectatomma tuberculatum, with gifts of sugary secretions. In return, the ants, which could easily eat the caterpillar or its adult butterfly form, defend the vulnerable caterpillars from other predators.
But this friendly give-and-take doesn’t last forever, work by Phillip Torres of Rice University in Houston, Texas and Aaron Pomerantz of the University of Florida, Gainesville, has now revealed. When the caterpillars have become butterflies, they turn on their protectors, plundering the source of their nectar.
This nectar is produced by organs called nectaries at the tips of new bamboo shoots, which are tended by ants. Using their mouthparts, they improve the flow from these nectaries, and stop them from running dry. The nectar is an important source of food for them, so they defend these nectaries fiercely.
Photo credit: Phillip Torres