Case for id,Langfield Edge,13 03 10

Hi all,found this case on cliff face at 6mm in length,made from bits of gritstone and debri,its empty unfortunately,so could prob be anything ?

Jailhole,Langfield Edge,20 02 10

Andy and me checked for Anomalous larva after dark,quite deep snow on hillside and rockfaces,and even though there were snow free patches of the foodplant Wavy Hairgrass, and it felt quite mild under the rockfaces,it was still below freezing and we never found any.i have found them in the past when icy, feeding,maybe it needs to be just above freezing before they start to feed,and who could blame em ! Found 2 green form on 14 12 09 when it was quite mild at aprox 12mm in size,incidently a green form larva that was kept a couple of seasons ago a male emerged ! do you sometimes wonder what you have got into !!