To provide a method for applying an insecticidal composition to an insect proof net so as to be able to improve durability to washing and continuation of the insect proof effect by treating the insect proof net which is generally commercialized with the insecticidal composition in order to prevent bite, discomfortable feeling and dermatitis caused by insect pests such as mosquito, gnat and ceratopogonid or diseases such as Japanese encephalitis or malaria caused by these insect pests, and to obtain the insecticidal composition for applying to the insect proof net.

This method for applying the insecticidal composition to the insect proof net so as to improve durability to washing and continuation of insect proof effect is characterized by immersing the insect proof net into a water bath containing the insecticidal composition comprising ethofenprox as an insecticidally active ingredient and a nonionic or anionic water-based polymer.