Pets are the most common source of a fleas in house or flea infestation. They get fleas from some other flea infected animal. An infected cat, dog, or even a raccoon or opossum may have went through your yard or neighborhood and the female flea laid eggs.
They are abundant in and around live oak trees where you will see them crawling on and around the surface of the tree. They often fall from the branches onto your yard, house, and vehicles. Now is the time to pay attention to where you sit outside and where you have children play. You don't want to get stung!