If your cat plays in water, you may want to take the collar off, put it in a plastic bag, and replace it once your cat is dry again. Most collars are listed as “waterproof” so a monthly bath should be ok, but too many and the insecticide could wear off. One thing that can reduce a collar’s efficacy is getting it wet multiple times per week. A few flea collars can kill adults within 24 hours and last up to 8 months making them comparable to other flea treatments for cats, like liquid drop treatments, without the mess. Some products combine adulticides with an IGR to reap the benefits of both – quick relief for your cat from bites and a way to avoid the spread of new fleas. Lighted Magnifying Glass That Stays Put.Best Lawn Care Service for Service Dogs.