Difference Between Lice and Fleas

The main difference between lice and fleas is that the lice mainly burrow into hair parts of the human body while the fleas are quickly moving small insects found mainly on animals. Only fleas can jump. Furthermore, the lice bite is comparatively less painful while fleas bite is more painful.  

Lice and fleas are two types of ectoparasites that live on the body of both humans as well as animals. Their bites can be painful and cause itchiness and swelling. 

Key Areas Covered 

1. Lice
     – Definition, Features, Lice Bites
2. Fleas
     – Definition, Features, Fleas Bites
3. What are the Similarities Between Lice and Fleas
     – Outline of Common Features
4. What is the Difference Between Lice and Fleas
     – Comparison of Key Differences

Key Terms 

Bloodsuckers, Diseases, Ectoparasite, Fleas, Lice, Vectors

Difference Between Lice and Fleas - Comparison Summary

Lice – Definition, Features, Lice Bites

Lice are small, bloodsucking insects that live on the skin of mammals and birds. The three types of lice found in humans are head lice (Pediculus humanus capitis), body lice (Pediculus humanus), and crab or pubic lice (Pthirus pubis). Lice bites can cause itching and irritations on the skin. In addition, body lice serve as vectors, transmitting several diseases such as typhus fever, trench fever, and relapsing fever.  

Difference Between Lice and Fleas

Figure 1: Lice Types

The three life stages of a louse are egg, nymph, and adult. Lice feed several times per day. Toxic reactions of the body to the injected saliva during biting can cause weariness as well as a general feeling of illness. 

Fleas – Definition, Features, Fleas Bites

Fleas are the small, wingless, bloodsucking insects that belong to the order Siphonaptera. The main characteristic feature of fleas is their ability to jump, which is facilitated by their long hind legs. Fleas feed upon mammals and birds. The three common types of fleas are rat fleas, human, fleas, and cat fleas. Their bites can cause the loss of blood, irritation, and serious discomfort. Rat fleas serve as a vector for the transmission of bubonic plague and flea-borne typhus. Cat fleas sometimes transmit tapeworms. Sand fleas or jiggers are another important type of fleas since they burrow into the human skin and cause infections.  

Main Difference - Lice and Fleas

Figure 2: Flea Anatomy

Fleas have a flat body, which is polished and hard. They have hairs and short spines that are directed backward. 

Similarities Between Lice and Fleas 

  • Lice and Fleas are two types of ectoparasites of blood. 
  • They live on humans or animals. 
  • Both are wingless and have 6 legs.  
  • They have piercing mouth parts, which facilitate biting and sucking blood. 
  • Their bites are painful and cause itching and swelling. 
  • Both can serve as vectors of diseases. 
  • Their eggs are oval-shaped. 

Difference Between Lice and Fleas 


Lice refer to small, wingless insects parasitic on humans and other mammals while fleas refer to small, wingless, jumping insects parasitic on mammals and birds. 


The lice belong to the order Phthiraptera while the fleas belong to the order Siphonaptera. 


Head lice, body lice, and pubic lice are some types of lice while rat fleas, human fleas, cat fleas, and sand fleas are some types of fleas. 


Looking at the habitat, the lice mainly live on hairy parts of the body while the fleas live in warm parts of the body such as armpits and behind the ears.  


Considering the physical appearance, the lice can grow up to 4.5 mm while the fleas can grow up to 1-4 mm. 


Also, the lice are oval-shaped while the fleas have a flat-shaped body. 


Furthermore, the lice can be dark gray in color while the fleas are dark reddish brown in color. 

Color of the Eggs 

In addition, the eggs of lice are tan or coffee colored while the eggs of fleas are white color. 

Mode of Nutrition 

Nutritionally, some lice are symbiotic scavengers while all fleas are blood parasites. 


Furthermore, the lice do not move long distances while the fleas move quickly. 


Moreover, the lice cannot jump while the fleas have long hind legs, which facilitate jumping. 

Life Cycle 

Besides, the life cycle of lice has three stages; egg, nymph, and adult while the life cycle of fleas has four stages; egg, larva, pupa, and adult.

Host Specificity 

Also, the lice show high levels of host specificity while the fleas show a comparatively low level of host specificity.


The lice are ectoparasites of humans and mammals and they have an oval-shaped body. Fleas are also a type of ectoparasites of mammals and birds and have long hind legs, which help them to jump. Both can serve as vectors that transmit diseases. The main difference between lice and fleas is the anatomy and behavior. 


1. Rozendaal, Jan A. “Bedbugs, Fleas, Lice, Ticks and Mites.” Vector Control – Methods for Use by Individuals and Communities, WHO, 1997, pp. 237–261, Available Here

Image Courtesy:

1. “Lice” By BruceBlaus – Own work (CC BY-SA 4.0) via Commons Wikimedia 
2. “Scheme flea anatomy-en” By Al2 – Own work (CC BY 3.0) via Commons Wikimedia 

About the Author: Lakna

Lakna, a graduate in Molecular Biology and Biochemistry, is a Molecular Biologist and has a broad and keen interest in the discovery of nature related things. She has a keen interest in writing articles regarding science.

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