Disclosed is a sustained release insecticide composition based on a porous, preferably tabletted structure. The insecticide is combined with a carrier comprising two components, a bulking material such as lactose and a porosity providing material such as calcium carbonate. The insecticide preferably is transfluthrin. Insecticide loads of 6-20 % by weight can be achieved, leading to a duration of action of 1-4 months.
