What ever it is starts in the autumn and carries on off and on over winter,
after the larvae of solitary bees I think

http://www.flickr.com/photos/89219640@N04/9623639468/

http://www.flickr.com/photos/8921964...n/photostream/
The holes are nearly always round about 2-3cm across and about 5cm deep with
a rounded bottom. the spoil is usually thrown to just one side.

(Its not our dog his holes are huge!!)

--
Charlie, Gardening in Cornwall
Holders of National Collections of Clematis viticella
and Lapageria rosea cvs
http://www.roselandhouse.co.uk