An agricultural pesticide composition containing: (a) a solvent which is a mixture of fatty acid alkyl esters corresponding to formula I: R.sup.1CO--OR.sup.2 (I) wherein R.sup.1CO is an aliphatic acyl group containing 12 to 18 carbon atoms and R.sup.2 is a linear or branched alkyl group containing 1 to 4 carbon atoms; and (b) a biologically active ingredient is described. A process of treating a target substrate with the composition is also disclosed.