How to Deal with Fleas: Before and After Spraying – Fleas, as far as pests go, aren’t the most threatening or repulsive pest. They don’t spread as quickly and rapidly as bed bugs, not as creepy as roaches or spiders, and certainly not as much of a problem as mice or rats. Fleas are small flat insects that live off the blood of mammals, and one of the most common types of fleas is the Domestic Cat Flea. This flea is the most common type of flea found in houses and properties, and while they’re relatively harmless to humans, they can cause massive problems for you, your belongings, and (if you have them) your pets. Here’s what to do when you’re encountering a flea infestation.