An entomologist prepares a sawfly antenna for GC-EAD (coupled gas chromatography - electroantennographic detection) analysis. GC-EAD is an analytical procedure that permits the rapid identification of compounds in complex mixtures that stimulate the olfactory sensilla of an insect. In other words, it can tell you what specific chemicals an insect can smell (and, to some degree, ones it can't), and it can use odors derived directly from natural sources. This information can be used to discover potentially useful compounds, such as sex pheromones, that alter the behavior of insects.