A pest-combating composition including soy methyl ester, and methods of combating pests utilizing same. Such composition in a preferred formulation may also include 2-undecanone. The composition may be constituted as a spray composition, lotion, paste, or other compositional form. Pests that may be usefully combated with such composition include mosquitoes, ticks, cockroaches, thrips, deer fly, gnats, and aphids.