Dutch ecologist Roxina Soler and colleagues have discovered that subterranean and aboveground herbivorous insects can communicate with each other by using plants as telephones. Subterranean insects issue chemical warning signals via the leaves of the plant, alerting  insects aboveground that the plant is already ‘occupied’.

Aboveground, leaf-eating insects prefer plants that have not yet been occupied by subterranean root-eating insects. Subterranean insects emit chemical signals via the leaves of the plant, which warn the aboveground insects about their presence. This messaging enables spatially-separated insects to avoid each other, so that they do not unintentionally compete for the same plant.

Via the 'green telephone lines', subterranean insects can also communicate with a third party, namely the natural enemy of caterpillars. Parasitic wasps lay their eggs inside aboveground insects.