Use of formulations comprising polyurea microcapsules obtainable by interfacial polymerization of diphenylmethylen-4,4'-diisocyanate (MDI), optionally in admixture with polymethylenepolyphenylisocyanate (PAPI), said formulations having a prolonged knockdown and killing effect longer than at least three months, preferably at least of 6 months, still more preferably at least of 9 months from the application, wherein the microcapsules comprise:an active principle selected from the pyrethroid and/orneonicotinoid classes,synergizing agents selected between PBO and Verbutin,the concentration of the active principle in the microcapsule as % by weight on the total of the microcapsule is comprised between 1% and 60%the average diameter of the microcapsules is comprised between 2 and 50 µm.
