Menthyl acetate (MA), a monoterpene is one of the main constituent of the peppermint essential oil obtained from the leaves of Mentha piperita. It has been reported to show ambulation-promoting effect in mice. Its fumigant and repellent activity has been evaluated on first-instar nymphs of the bloodsucking bug Rhodnius prolixus. The decomposition of MA in an atmospheric flow reactor and a low-pressure flat flame has been investigated by molecular-beam mass spectrometry (MBMS).