The answer to 'how did flea get in my house' is that fleas can enter your home in several ways, such as on pets, through open doors and windows, or even on your clothing. Fleas are small, wingless insects that can jump long distances and quickly infest your home.
Common causes of a flea infestation include bringing home a pet with fleas, allowing pets to roam outside, or having wildlife like rodents or stray animals near your home. Symptoms of a flea problem include seeing the fleas themselves, finding flea dirt (flea feces) on your pet or in your home, and experiencing itchy bites on your skin.