Coleophora serpylletorum is a moth of the Coleophoridae family. It is found from Denmark and Latvia to Spain, Sardinia, Italy and Greece and from Great Britain to Romania. It is also present in northern Russia. The wingspan is about 9 mm. The larvae feed on Thymus praecox and Thymus serpyllum. They create an untidy composite leaf case of about 9 mm with a mouth angle of 90°. The larva completely mines out a leaf, usually at the top of a twig, often while attached to the leaf margin. When the leaf is emptied it is cut off and is added to the case. Full-grown larvae can be found in June.