Wingspan 10 to 13.5mm. The adult moth is rather long and thin in shape and brown in colour.

The larvae feed on Sallows (and on Bog Myrtle in other areas of the British Isles). The larva forms a composite case of three leaf fragments sealed together into an irregularly shaped tube, adding each fragment at the oral end so that the anal end is older, and therefore darker in colour.  The case often has a woolly appearance depending on the sallow species used to construct it.  It overwinters attached to a twig, resuming feeding in Spring.  The larval feeding makes white blotches on the leaves, each with a central hole where the case was attached. 

Similar composite cases are made by Coleophora binderella on Alder, etc.

Adult Case

larval stages: Photograph the mature case, and note the host species in the comments.

In any areas where its host plant grows.

The adult moths fly in a single generation emerging in June and July.

The eggs of this species are laid on the leaves of Willow, Bog Myrtle or, in Scotland, occasionally Birch.

The moth is common in areas where its host plant grows, throughout the whole of Britain, except the far north of Scotland. In the Butterfly Conservation’s Microlepidoptera Report 2011 this species was classified as common.

It appears to be uncommon in Leicestershire and Rutland, where there are few records. L&R Moth Group status = D (rare or rarely recorded).

http://www.leafmines.co.uk/html/Lepidoptera/C.lusciniaepennella.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/gelechioidea/coleophoridae/coleophora/coleophora-lusciniaepennella/