Hundreds of aroused male garter snakes will swarm to a single female after just one whiff of the pheromone cocktail she produces during mating season. A research team led by Oregon State University’s Robert T. Mason now show that male snakes can be diverted from their normal copulating course by other males who have been exposed to the female hormone estrogen (J. Exp. Biol., DOI: 10.1242/jeb.064923). The team found that male snakes implanted with 17β-estradiol started producing female pheromones, namely long-chain methyl ketones. These female impersonators were then “vigorously courted” by normal, unsuspecting male snakes, who couldn’t distinguish the implanted males from female snakes, the researchers say. When the team removed the estrogen implants from the snakes, they stopped producing pheromones, and the normal males stopped finding them so attractive. “This study gives important insight into the control of pheromone production in snakes and potentially other reptiles,” comments Stefan Schulz, a chemical ecologist at the Technical University of Braunschweig, in Germany. The results could be of wide importance, Schulz adds, because estrogen-mimicking pharmaceuticals and other chemicals entering the environment could impact snake reproduction.