Flea Bites vs. Lice – How Do You Tell Them Apart?

Both fleas and lice are blood sucking ectoparasites that live on animals as well as on humans. I often get queries from readers asking about the main differences between fleas and lice. So today, I am going to cover the all important topic of Flea Bites vs Lice and the characteristics which set them apart. I will also show you some of the best ways to treat these parasites at home.

Fleas vs Lice – What is the difference?

Both fleas and lice are wingless insects. They are equipped with piercing mouthparts that allow them to bite through human or animal skin and suck blood. Flea bites can be painful and may cause itchiness, swelling and flea allergy dermatitis. Lice bites cause similar symptoms and may result in rashes. Furthermore, both parasites could be vectors of diseases which they can transfer from one host to another. Here are their individual characteristics:


Fleas have a flattened body which makes them run rapidly through their host’s hair. They are also equipped with claws that enable them to hold on to the host. They have a third pair of legs which are very strong and enable them to jump from host to host. Fleas need blood meals to complete their various life cycle stages but they can also leave the host for a few days to lay eggs or to mate. Typical hosts of fleas are animals such as dogs, cats, pigs, rats and mice, but in the absence of these hosts, they may feed on humans. Fleas are vectors of bubonic plague and anthrax germs may also be present in their saliva. Chances of developing anthrax grow when the germs get rubbed or scratched into the host’s skin.

Flea bites

Flea bites typically appear as swollen, red welts. The swelling and itchiness can get extremely uncomfortable. In young animals like puppies and kittens, fleas can also cause symptoms of anxiety. Excess itchiness could also lead to flea allergy dermatitis and may even turn into anemia in weaker animals.


The bodies of lice, like fleas, are also compressed dorsally which enables them to move easily through the host’s hair. Like fleas, lice have claws to hold on to the host’s body. But this is where the similarities between fleas and lice end. Lice spend their entire lifetime on the host’s body and they do not leave the host like fleas do for laying eggs. The eggs, which are called nits, hatch into nymphs and are yellowish oval particles that are attached to the host’s hair shaft. Lice travel from one host to another through direct close contact.

Lice bites

Lice bites lead to extreme itchiness and irritation. Typically, lice are found in the scalp and pubic areas in humans. The bites of lice, when scratched, could develop secondary skin infections which are harder to treat. These can even turn into sores filled with pus. Lice are also vectors of diseases like typhus and European relapsing fever. The lice excreta could also get rubbed into the bitten areas of the scalp causing serious infections.

So how do you tell Fleas and Lice apart?

  • Flea bites on humans usually occur in irregular groups of several dozen or more. There is also a central spot surrounded by an erythematous ring. Chronic exposure to flea bites can cause urticaria which is characterized by severe itching. Flea bites are also concentrated on lower limbs, legs and feet and also around the areas where the clothing is tight, such as the waistband etc. A heavy flea infestation can be recognized by marks on clothing and beds. This is the undigested blood ejaculated by the fleas.

  • Pubic lice can cause bluish discoloration of skin in humans while head lice bites are pustular and may cause blisters on head, scalp and neck. The skin of people who continually harbor body lice is usually hardened and darkened.

There are many different species of fleas and lice. While some of them do not cause any disease, their biting can be a serious nuisance. I hope this guide helps you understand the differences of flea bites vs lice and that it helps you make an informed decision for their prevention and control. Good luck!