Blastobasis lacticolella

I swear I am gong to fill the caps of these tubes with blue-tack or something. Every invertebrate of whatever kind always wants to sit inside the cap so you can't see them! The dark marks on this species seem to be quite variable but I think the ID is ok - plenty of paler ones barely have the main dark patch featured at all. You can see it's there, but it's not particularly strong.