Difference Between Lice and Crabs

Lice and Crabs are two types of insects that happen to take place in the human body. They belong to the Phthiraptera species. There are about 5,000 variants of Phthiraptera.

Generally, they feed themselves by consuming human blood and there is some specific area they live in.

Lice and Crabs can not fly or walk-in general, but the only way to come in contact with such insects is by the physical touch from the other person who might carry such insects.

Lice vs Crabs

The main difference between Lice and Crabs is that they occur or build up their space in different sections of the body. It has been noticed that lice or head lice specifically take place around the head parts such as hair, at the back of the neck, or in the posterior of the ears. While on the other hand, Crabs happen to take place in the genital area of the human which includes armpits, chest hair, also in pubic area.

Lice vs Crabs

The louse is a small insect that generally lives in our head portion and the area where it stays itches a lot as they suck blood from that area for their living.

The average measurement of lice is about 2.1 mm to 3.3 mm in length.

On the other hand, if a person notices some kind of discomfort and itchiness in their genital areas and sees some small insects then they are addressed to be Crabs.

The size of a Crab is very tiny and hence it measures around 1.1 mm to 1.8 mm in length.

Comparison Table Between Lice and Crabs

Parameters of ComparisonLiceCrabs
Survival Time After the Separation of HostAn adult head lice survive for about 24 hours after it gets separated from its host. Within a period of 24 to 48 hours from the host, the crabs tend to die.
InfestationAbout 37% of infestation is generally seen for the head lice. The infestation of crabs is comparatively lesser with a rate of 2%.
Number of Eggs per DayOn average, a female louse lays about six eggs per day. In crabs, only three eggs are laid daily.
ColorThe lice are generally light grey. Crabs happen to be light brown.
AppearanceThe average appearance of head lice is fat and a bit elongated. Crabs are shorter and comparatively thinner than head lice.

What is Lice?

In simple words, lice or head lice refers to those small insects that are present in the human body, and therefore lice take place in the head portion.

Lice are irritating since it causes some kind of itchiness in the head. Head lice live on the blood that they suck from the head.

And the itchiness and discomfort are caused because of their movement or when they suck blood. Generally, head lice infest by 37%. They are light grey and hence it is slightly difficult to identify them in the hair.

The normal measurement of head lice is about 2.1 mm to 3.3 mm. Also, it has been determined that a female louse is bigger than the average male lice.

When an adult head lice get separated from its host, it can not survive more than 24 hours. This is because of the cycle but in general, adult lice live for about 28-30 days.

The symptoms by which one can find that they have lice are if the person feels severe itchiness all the time, discomfort, blood, etc.

Such insects can only come via head-to-head contact with the opposite person, usage of other towels and combs, etc.

Therefore, you should not share some personal things with anyone. Maintaining hygiene, medicated shampoos, soaps, etc can only cure this problem.

What is Crabs?

Crabs are tiny insects that are generally light brown. Crabs are blood-sucking insects. The commonplace where we can detect crabs are the genital areas such as armpits, pubic region, chest hair, legs, etc.

Crabs are so tiny that we can not easily identify them, but if we feel itchiness or discomfort in such areas and can find small insects then is it called crabs.

The general life cycle of crabs is estimated to be of 28-30 days, but if it gets separated from its host then it dies with a period of 24 – 48 hours.

Generally, such insects are spread during sexual acts. And it can only move via hair or skin. It measures about 1.1 mm to 1.8 mm, therefore it can be identified in a single go.

Also, it was noticed that crabs lay about three eggs a day and specifically on the hair shaft of the genital areas.

One can feel very irritating and itching almost all the time. Therefore, one should immediately take against it if detected, before making the situation more worse or spreading over others.

It can even create rashes or infections. Hence, immediately consult a dermatologist who can prescribe some medications to get rid of crabs.

Main Differences Between Lice and Crabs

  1. An adult louse can only survive for 24 hours after the sepaaration from its host and on the other hand, after the sepration of the host and the adult crabs, it can die within a small period of 24 to 48 hours.
  2. It is noticed that only 37% of head lice infest and on the other hand, only 2% out of 100% infests in crabs.
  3. Per day, about six eggs are laid by the head lice and on the other hand, crabs lay comparatively lesser eggs than head lice and that is three eggs per day.
  4. Usually, head lice are noticed to be in a light color, and on the other hand, the light brown color insects in genital areas are represented as Crabs.
  5. The shape of head lice is flat and elongated and on the other hand, crabs come in a smaller appearance.
Difference Between Lice and Crabs


Certain insects that do not possess any specific work and therefore, head lice and crabs are amongst them.

Their survival depends upon the human blood and hence they suck blood from their respective regions which causes itchiness and discomfort. The head lice live in the head area and the crabs live in genital areas.

They can only be cured by using some medications and cleanliness is a must. There are several shampoos, ointments, etc are available which can kill this insect.

One can also try out some home remedies and where neem leaves take up a major role.


  1. https://www.cabdirect.org/cabdirect/abstract/19452700873
  2. https://www.cell.com/trends/parasitology/fulltext/S0169-4758(00)01694-X
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/pmc1070891/
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