Fleas commonly make their homes in areas where their primary hosts—typically animals—spend a lot of time. This includes animal beds, burrows, and nests, which provide a warm, sheltered environment close to a host for feeding. Fleas rely on their hosts for sustenance; they need blood to survive and reproduce, making it essential for them to be close to suitable animals.
While fleas can occasionally be found indoors or in human dwellings, especially if pets are present, the most prevalent and ideal environments for them are indeed those associated with animals. Other choices, like under rocks or inside homes with no pets, do not provide the conditions that fleas prefer, as they lack the necessary hosts for feeding. Thus, the habitats where fleas thrive are primarily linked to their animal hosts.