The Lifecycle of a Pinworm

Lifecycle of a Pinworm

Without experiencing pinworms firsthand, many people have never heard of them. Pinworms are the most common intestinal parasite in the United States. It is safe to say that many families have had to deal with worms in kids from time to time. Although caregivers tend to be embarrassed when their children have pinworms, they shouldn’t be.

You can be infected with pinworm no matter how clean or diligent you are. An infection is passed from person to person and adults can carry eggs even if they have no symptoms. The worms will carry on their life cycle if they are not treated fast and efficiently.

A quick breakdown of the lifecycle of a pinworm shows you just how arbitrary contracting a pinworm infection is.


The lifecycle of the pinworm begins with microscopic pinworm eggs. Able to survive on most surfaces for 2 to 3 weeks, pinworms can be picked up anywhere.  Due in part to their not-so-hygienic tendencies, school-age and preschool children are some of those most likely to get a pinworm infection.


After pinworm eggs are ingested, they travel through the stomach to the large intestine. On the way, eggs hatch and reach sexual maturity. Adult female pinworms then migrate from the large intestine to the anal area, where new eggs are laid.

The egg-laying process typically happens in the middle of the night or early in the morning, which is why we recommend performing the “Scotch® Tape Test” after your child has gone to bed. It’s the best time to catch the little pests!

Adult pinworms look like a piece of thread. They are white in color and measure about 1/2” in length.


Retroinfection occurs when the eggs that are deposited on the perianal skin hatch. These juvenile pinworms will crawl back into the anus and mature into adults, allowing the process to repeat itself. It takes just 6 hours for these eggs to mature and become infective.


Of course, with tiny worms crawling in their behinds, it’s easy to understand why children infected with pinworms will start to scratch. And once they do, the contamination process begins again. Hands, underwear, pajamas, bedding and any surface your child touches after scratching their behind can easily become home to the microscopic pinworm eggs.

For more information on cleaning after a pinworm infection, read our blog post titled: How Do You Get Rid of Pinworms in Your Home?