Many people probably think they know what a cocoon is. Well, the answer is actually more complex than it seems. Certain types of insects build cocoons, and cocoons are different from other types of insect casings. How do you know the difference, and which insects are responsible for creating them?

What is a Cocoon?

The Pupal Stage

The first thing to understand about cocoons and other pupa casings is the purpose that they serve. Insects that create these undergo a full metamorphosis with four complete life stages: egg, larva, pupa and adult.

Insects will build cocoons or other casings during the pupal stage of development. This is when the most dramatic changes in the insect’s appearance and behavior occur, and it is also when they are at their most vulnerable to predators and other hazards, and need extra protection. While the insect lies still to complete its development, the cocoon helps ensure that it reaches adulthood unharmed.

Cocoons vs. Pupa Casings

As mentioned, cocoons are not the only type of insect casing. They are commonly confused with other types of pupa casings, but have a slightly different appearance and composition, as cocoons are made of silk.

Which Insects Make Cocoons?

There are a number of insects that create cocoons, and the list might surprise you. These include:


A common pest in the homes of pet owners, fleas reproduce rapidly, with a single flea laying up to 50 eggs a day. Larvae hatch from these eggs, form cocoons and pupate for 2-4 weeks, after which adult fleas emerge. Flea cocoons can be resistant to some pesticides, which can explain why they can be so difficult to get rid of when an infestation is present.

Moths and Butterflies

Nearly all species of moths and some species of butterflies create cocoons. Caterpillars, the common name for the larval stage of these insects, spin silk to create the cocoon. Butterflies that do not spin cocoons will have a chrysalis, a covering similar to a pupal casing.


These small, brownish-black insects are commonly found near bodies of fresh water, such as ponds, lakes, rivers, creeks and streams. Certain species of caddisflies will form cocoons using sand, twigs and other types of debris found along the bottom of the water, which will serve as camouflage and protection from predators throughout the pupal stage.

Parasitic wasps

Some species of wasps attack other insects, like aphids, caterpillars, beetles and flies, and use these as hosts to lay their eggs. After the wasp larvae emerge, they will form cocoons in or nearby their hosts.

Finding Cocoons in Your Home

If you have certain types of insects in your home, there is a chance you may find cocoons. Flea cocoons are generally too small to be seen with the naked eye. However, clothes moths, which feed on a variety of household items like wool, yarn, upholstery and paper, may form visible cocoons.

As with any other pest problem, proper identification is crucial to controlling the issue. If you find cocoons in your home, contact the pest control professionals at Terminix®. They can properly identify the insects responsible and provide treatment options.