Flea Cocoons

This page provides a quick summary of flea cocoons, in the form of a FAQ. Click on the answers for detailed information, including citations.

What do flea coocons look like?
Flea cocoons are composed of a sticky silk-like material. Debris adheres to the structures and camouflages them, making them look like lint balls. The oval shaped cocoons are 4-5 mm long and 2 mm wide.

What flea stages are found in cocoons?
There are 3 cocooned stages. Larvae in the cocoon are called prepupae. After molting they become pupae. Then after another molt they reach adulthood (pharate adult).

Where do fleas cocoons live?
Flea cocoons are found where larvae live, most commonly deep within carpets.

How long do flea cocoons live?
Once larvae form cocoons, they will pupate into adults in 7 to 19 days. However, the adults may remain inside the cocoons for extended periods.

Do flea cocoons go dormant
Yes. Cocooned adults can enter into a quiescent (dormant-like) state for up to 5 months.

What percent of infestations are cocoons?
Cocooned stages make up 8-10% of infestations.

Does vacuuming kill flea cocoons?
Depending on the carpet type, vacuuming can remove up to 63% of flea cocoons. 100% of those removed will be killed in the process.

Do flea cocoons drown?
The cocoon itself isn’t a barrier to water. However, cocooned stages are difficult to drown. Most will survive 12 hours of submersion. However, they won’t survive a washing machine, due to the action, heat, and detergent.

Do fleas have to pupate within cocoons?
No. Sometimes fleas pupate without cocoons. They are called naked pupae and can still reach adulthood successfully.

What is the purpose of the cocoon?
The cocoon allows pre-emerged adults to enter into a dormant-like state for up to 5 months. The structure also protects developing fleas from predators, both physically and by camouflaging them.

What’s the best way to kill flea cocoons?
Please see our page on How to get rid of fleas for control information. Cocooned stages are the most difficult to kill, because they’re protected deep within carpets. Vacuuming can remove some, but often patience is required while waiting for the adults to emerge and die.

Please leave a comment below if you have any questions that weren’t addressed, and I’ll add them to the list.