Fleas thrive in warm or humid weather and can lay up to 50 eggs each day. Their bites leave nasty sores. Some people develop rashes when bit by fleas. Fleas usually just spread misery to infested households. If conditions are right, they can live up to two years, and their eggs and larvae can hide out in bedding, clothes, and tiny cracks in the house.
Adult fleas are no larger than 1/8 inch long. They are reddish-brown, wingless insects that are laterally compressed, so they look as if they are walking on edge. They have piercing-sucking mouthparts which they use to obtain blood meals from their hosts.
Your lawn can harbor a significant number of fleas which can hitch a ride on your pet. One of the first signs your pet has fleas is "flea dirt" - black flea droppings left on your pet's coat. See your vet for proper treatment. Even if your pet avoids an infestation, he or she could still track the insects into your home.