The answer to 'when to treat for flea' is that the best time to treat for fleas is when you first notice signs of an infestation, such as seeing fleas on your pets or in your home. Fleas can reproduce quickly, so it's important to act fast to prevent the problem from getting worse.
Typically, the peak flea season is in the warmer months, from late spring through early fall. However, fleas can be a problem year-round, especially in warm, humid climates. It's a good idea to check for fleas regularly and be prepared to treat your home and pets as needed.