On Thu, 29 Aug 2013 16:27:07 +0100, "Charlie Pridham"
wrote:

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!!)

Before I saw the estimated width my immediate reaction was badger
scrapes. The spoil pattern is very similar to those I have seen, but
the width is more like 4 cms. Solitary bees and the green woodpecker
tend to make holes of the size you indicate but there is little or no
spoil pattern, usually just a small divot in the case of the
woodpecker.
--
rbel