The insect-trapping Nepenthes rafflesiana, commonly known as Raffles’ pitcher plant, doesn’t always capture the ants and other prey that are drawn to it. The rims of some of the pitchers of the viny plant, which grows in the tropical lowlands in parts of Southeast Asia and the Malay Archipelago, are slick when conditions are humid, so insects walking there readily slip into the enzyme-rich, prey-digesting fluid inside the vessel. But for several hours during the hottest part of the day, the edges of those pitchers (one shown above) are dry, which allows foraging ants to collect nectar from inside the rim of a pitcher and then return to their colony to alert their kin to the plant’s bounty and its location. In a field experiment, researchers used a dilute solution of sugar to continually wet the edges of some pitchers; others were left alone. Overall, the pitchers that were left alone captured more than 36% more ants than the always wet pitchers, the researchers report online today in the Proceedings of the Royal Society B. The findings, the scientists say, are the first to back up a decades-old theory that pitchers with intermittently slick rims would end up capturing more prey by allowing scout ants to safely escape and thus lure their colony mates.