Unknown bug on tree trunk

Unknown bug on tree trunk

Observation - Unknown bug on tree trunk - UK and Ireland. Description: Spotted this in the enlarged photo I took of a lichen on the trunk of a young walnut tree. That observation is http://www.ispot.org.uk/node/6976

Spotted this in the enlarged photo I took of a lichen on the trunk of a young walnut tree. That observation is http://www.ispot.org.uk/node/6976