Oxford Feb 08 bugs

Oxford Feb 08 bugs

Observation - Oxford Feb 08 bugs - UK and Ireland. Description: These bugs appeared suddenly on the trunk of a curly willow in our garden back in 2008, and just as suddenly disappeared a few days / a week or so later. They remained huddled closely together while in that location, not really moving much at all. They we

These bugs appeared suddenly on the trunk of a curly willow in our garden back in 2008, and just as suddenly disappeared a few days / a week or so later. They remained huddled closely together while in that location, not really moving much at all. They were several millimetres long and dark grey in colour with spots and a protuberance on their backs as can be seen on the photos. No idea what type of insect they are.