The threat of fleas is more than just a nuisance. A few fleas can quickly become a full-blown infestation, which can be irritating and costly. The best way to fight a flea infestation is to make sure that it never occurs. If you're using a flea preventive, use it year round. Weather patterns are unpredictable and flea season can start before you're ready.
All pets in your house should be treated for fleas. If you have more than one pet, treat them ALL for fleas.
The best way to deal with a flea problem is before you have one, and the best time to use flea control is before you see fleas. It takes much less effort to prevent flea infestations than it does to get rid of them.
For more information, please read the story How to Control and Prevent Fleas on Your Cat