Fleas have a complex lifecycle involving eggs, larvae, pupae, and adults. Eggs are laid on pets and fall off into the environment like carpets. Larvae feed on skin flakes and flea droppings before forming pupae. Adults emerge to feed on pets. Detection involves combing pets over white paper to see flea dirt or using flea combs. Treatments involve vacuuming and washing bedding to control the environment along with spot-on flea treatments for pets or oral medications. Common spot-on treatments are Frontline and Effipro which spread through the skin to kill fleas, while tablets like Capstar work systemically.