
Appearance
The wingspan of adult stage moths is between 25 and 35 mm. Their pattern of tan, brown and white make the adults difficult to see against oak bark.Adults fly during July and August. The larvae construct communal nests of white silk from which they crawl at night in single file, head to tail in large processions to feed on foliage in the crowns of trees, returning in the same manner.
Oak is its preferred food source, but it also attacks hazel, hornbeam, sweet chestnut, birch and beech.

Distribution
The moths are widely distributed in central and southern Europe, and are occasionally found as far north as Sweden. In the southern countries of Europe the populations are controlled by natural predators, but these predators do not exist in northern Europe. Their range is expanding northward, possibly or partly as a result of global warming.References:
Some text fragments are auto parsed from Wikipedia.