nthony Cognato, an entomologist at Michigan State University, is a bark beetle expert. He's made a career out of collecting, identifying, and classifying the insects—members of the subfamily Scolytinae—that make a living by cultivating fungal gardens in tunnels they bore in dead trees. Even though he's an expert in bark beetles, Cognato can still be surprised by the organisms he's devoted his career to studying.
A few years ago, Cognato's graduate student, Jiri Hulcr, spent 18 months in the rainforests of Papua New Guinea, surveying the island's bark beetle fauna across a 1,000-kilometer transect. Hulcr set up three sampling sites, each 500 kilometers apart, by felling trees and waiting for bark beetles to inhabit the dead wood and establish their fungal gardens, called galleries. As he collected beetles, Hulcr began to notice a pattern that he showed to his advisor during Cognato's visit to the field sites. ...