Insecticides?

Insecticides only kill of the adult fleas. The vast majority of any flea population consists of eggs, larvae and pupae, just waiting to hatch out into adults. That is why an insecticide does not do the job. It only kills 15% of the population. Check out the Life Cycle of the flea here. To stop the juvenile fleas from developing you must use an Insect Growth Regulator. It does not kill the adult fleas (there are lots ofinsecticides to do that) but it does break the cycle and put an honest end to flea infestations.