The number of fleas needed to be considered an infestation depends on several factors, including the size of the house and the number of pets living in the house. However, in general, if you see more than a few fleas in your home, you may have an infestation. A female flea can lay up to 50 eggs per day, and those eggs can hatch within 2 to 14 days, so a flea infestation can grow rapidly. If left untreated, a small number of fleas can quickly turn into a large infestation. In addition to seeing fleas, other signs of a flea infestation include flea dirt on carpets or furniture, pet scratching, and bites on humans or pets. If you suspect a flea infestation in your home, it's important to take action quickly to prevent the infestation from getting worse.