And why are they so hard to control?

Adult fleas are reddish-brown insects with a body that is compressed from side to side^[5]. While visible to the naked eye, they are so small you could line about eight adult fleas end-to-end in 1 inch.

Fleas are wingless, but possess incredible jumping ability. This enables them to easily jump from ground level to “ambush” a pet.

Fleas feed on blood, and female fleas consume about 15 times their body weight each day^[6]. This poses a threat of anemia to puppies as well as heavily infested or debilitated adult dogs. Incompletely digested blood is excreted and dried to form what is commonly referred to as “flea dirt.” This serves as food for developing flea larvae and is one way veterinarians and pet owners can identify an infestation.

Why do they have to eat so much? They need nourishment to reproduce. In fact, adult female fleas may begin to feed on an animal within minutes of contact and actually begin to lay eggs within 24 hours. These eggs then fall off the dog and become larvae. The larvae turn into pupae which are generally more impervious to flea control products applied to the animal or it's environment.

Adult fleas erupt out of their pupal stage, or cocoon, and quickly find a host, such as your dog. Because these pupae can be found almost anywhere, including your own living room, it seems to pet owners that fleas appear out of nowhere.

There are numerous misconceptions about flea biology, one of the most common being that fleas leave their host regularly^[5]. But once an adult flea begins feeding, it will die within 24 hours if removed from its food source. It also is rare for a flea to jump from one host to another, commonly known as “hitchhiking,” unless the flea population approaches 200 fleas per pet. Studies show that even when pets sleep together, fleas generally do not transfer hosts^[5].

Fleas can make you and your dog miserable

Depending on your dog’s age and overall physical condition, fleas can pose a serious threat to its health.

• Fleas can cause severe discomfort for dogs, including scratching, chewing, biting and restlessness
• Fleas are the source of flea allergy dermatitis (FAD), the most common veterinary dermatological condition^[7]
• Severe flea infestations can cause anemia, especially in puppies or debilitated adult dogs
• Fleas also can transmit tapeworm infection

In humans, fleas can transmit murine typhus, bartonellosis (the agent causing cat-scratch disease) and bubonic plague^[5]. What’s more, eliminating fleas in a house or apartment can be costly and inconvenient, often requiring repeated insecticide treatments.