Plants defend themselves against herbivory through several means, including the production of airborne volatile organic compounds (VOCs). These VOCs benefit plants by attracting natural enemies of their herbivores. The pea aphid, Acyrthosiphon pisum, is able to feed on its host plant, Vicia faba, without inducing detectable changes in plant VOC emission. Levels of VOCs emission are not significantly different between control plants and those fed upon by aphids for up to 5 days. Using a second herbivore, the beet armyworm caterpillar, Spodoptera exigua, we demonstrate that several expected caterpillar-induced VOCs are reduced when co-infested with pea aphids, thus demonstrating that pea aphids have the ability to inhibit the release of certain VOCs. This study shows, for the first time, that aphids not only avoid triggering plant volatile emission, but also can actively inhibit herbivore-induced volatiles.