Enterobius Vermicularis Life Cycle


Enterobius Vermicularis is the scientific name for pinworms, threadworms or seat worms that fall under the family Oxyuridae and the order Ascaridida. Popularly known to be the ‘human pinworm’, as they are parasites found in the intestines of human beings, prominently in children. Apart from human beings, they are also found in some vertebrates. One way to differentiate between the gender of pinworms, is to notice that female pinworms are physically longer than male pinworms. Female pinworms measure up to 13 mm, while male pinworms measure up to 5 mm. The infection caused by pinworms is called enterobiasis, but sometimes referred to as Oxyuriasis.

The complete life cycle of Enterobius Vermicularis occurs in the gastrointestinal tract of human beings. Now, let’s look at the life cycle of a pinworm to understand them better.

Life Cycle of Enterobius Vermicularis (Pinworm):

1) The Egg – Stage 1 –

After fertilization, the female pinworm lays eggs on the perianal skin, which is the rim of the anus. This usually this occurs when eggs enter through the mouth with hands that have scratched the perianal region. When this pinworm moves in the perianal area, it causes itching in that area. Infection also occurs if eggs are exposed to contaminated clothes, bed linen and other surfaces.

2) The Larvae – Stage – 2 –

Once the eggs have been ingested, they tend to hatch in the small intestine of human beings. The larvae inside the eggs grow in 4 to 6 hours, depending on proper climate conditions; where the eggs become infective. And the adult worm established themselves in the colon region.

3) The Adult – Stage 3 –

The time period from ingestion of eggs to oviposition by adult females is around one month. Gravid (pregnant) females shift nocturnally outside the anus and oviposit while crawling on the perianal skin of the anus. And the life cycle of Enterobius Vermicularis continues.


The adult pinworm lives for around 2 months.The female adult pinworm measures up to 13 mm and the male adult pinworm measures up to 5 mm and their total lifespan is about 2 months.

Their entire life cycle exists inside the human body, since they develop and reproduce inside human intestines.

To explore more information about enterobius vermicularis and other worms, register with BYJU’s Biology.

Frequently Asked Questions on Enterobius Vermicularis Life Cycle

What are the symptoms of a pinworm infection?

A pinworm infection causes severe itching in the region around the anus that leads to disturbed sleep and restlessness.

Who are prone to pinworm infection?

People who are at risk of pinworm infection are thumb sucking infants, school-aged children and the household members of their family.

Where are pinworms found in the body?

Pinworms are white, round-like worms found in the colon and rectum area of the human body. The eggs, later under favourable conditions, hatch inside the small intestine of the body.

Test your Knowledge on Pinworms Life Cycle!

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