A single-phase emulsifiable concentrate composition, comprising the pesticide tefluthrin, a solvent suitable for dissolving tefluthrin, a water-soluble emulsifying surfactant system enabling an oil in water emulsion to be formed when the emulsifiable concentrate composition is diluted with an aqueous solution, a non-aqueous polar solvent for diluting the water-soluble emulsifying surfactant system, and a C2-C10 alcohol to provide physical compatibility between the hydrophobic solvent for dissolving tefluthrin and the hydrophilic emulsifying surfactant system and the hydrophilic non-aqueous polar solvent. Preferably, the C2-C10 alcohol is selected from ethanol, 1-hexanol, 1-octanol and 1-decanol. The water-soluble emulsifying surfactant system may comprise an alkyl polyglycoside surfactant, a polyalkylene oxide block copolymer and/or a polyaryl-phenyl ether phosphate. Preferably, the non-aqueous polar solvent is selected from propylene glycol, dipropylene glycol and dipropylene mono-methyl ether, or mixtures thereof. The solvent for dissolving tefluthrin is preferably an aromatic hydrocarbon. Also disclosed is an insecticidal composition obtained by diluting the emulsifiable concentrate composition in a suitable carrier, such that the final concentration of tefluthrin is between 0.01-10 wt%. The carrier is preferably an aqueous carrier, such as water or liquid fertiliser. The dilute composition may be applied to the plant propagation material, plant or locus thereof.
