A composition comprising a microcapsule having a polyurea wall encapsulating a pyrethroid insecticide, wherein the polyurea wall of the microcapsule is made of polyurea polymers derived from a mixture of aromatic polyisocyanate (A) and aromatic diisocyanate (B), the weight ratio of (A) to (B) is 1:1, the polymer (or wall) content of each microcapsule is from 6 to 9% by weight, and the amount of the pyrethroid insecticide is from 15 to 60% by weight, each based on the weight of the microcapsule； such a composition providing improved worker exposure characteristics.
