Coleophora adjunctella is a moth of the Coleophoridae family. It is found from Fennoscandia and northern Russia to Romania, Italy and France and from Ireland to Ukraine and southern Russia. The wingspan is 8–10 mm. There is one generation per year with adults on wing from late June to July in western Europe. The larvae feed on Juncus gerardii. The larva feeds internally on the seeds and then from a case, which consists of a seed capsule. Larvae can be found from August to May.