Soybean volatile compounds, soybean aphid-induced volatile compounds and soybean aphid sex pheromones are semiochemicals of the invention used to suppress soybean aphid population. Methyl salicylate is an embodiment of a soybean aphid-induced volatile compound useful in the invention. Benzaldehyde is an embodiment of a soybean host plant volatile compound useful in the invention. Also useful as sex pheromones are nepetalactol and nepetalactone. The compounds may be blended in a preferred embodiment.