These larvae live inside a flat, oval-shaped casing (or cocoon) that protects them while they grow and change. The cocoon is made from silk mixed with bits of sand, dust, or even soil. It usually has a small opening at one or both ends so the larva can move in and out.
However, the larva rarely leaves its case completely — it usually only pokes out halfway, and only when it’s looking for food.

Sources say that this moth, which is only about 13mm long, can lay up to 200 eggs at a time. When the eggs hatch, the larvae build their cocoons and hide in quiet, undisturbed parts of the house.
They also like to eat fabric and even small spiders, often sticking to old spider webs.
Since these creatures prefer warm places, it’s a good idea to regularly check warm areas of your home — especially behind furniture, near ceilings, or other cozy spots — to keep them from settling in.