Carnivorous plants have developed a variety of unique mechanisms to trap their prey, and researchers have another to add to the list: a pitcher plant that uses the impact of rain drops to flick insects into the trap. The full report is published June 13 in the open access journal PLoS ONE.

The Nepenthes gracilis pitcher plant, found in southeast Asia, has a unique, semi-slippery wax crystal surface on the underside of the pitcher lid. The researchers, led by Ulrike Bauer of the University of Cambridge, found that ants could cling to this surface under normal conditions, but a rain drop falling on the lid is enough to dislodge the insects, catapulting them into the pitcher where they are digested. This behavior can be seen in videos accompanying the published article.

This is an N. gracilis pitcher with a visiting Polyrhachis pruinosa ant.

(Photo Credit: From: Bauer U, Di Giusto B, Skepper J, Grafe TU, Federle W (2012) With a Flick of the Lid: A Novel Trapping Mechanism in Nepenthes gracilis Pitcher Plants. PLoSONE 7(6): e38951. doi:10.1371/journal.pone.0038951)