An insect repellent composition comprising the dihydronepetalactone stereoisomer 1 S,9S,5R-6R-5,9-dimethl-3-oxabicyclo[4.3.0]nonon-2-one in an amount of from 0.001% to 80% by weight of the total weight of the composition together with one or more of adjuvant, a carrier and an insect repellent compound that is not a dihydronepetalactone.