Sac Spider species Clubiona sp
In Western Europe there are about 20 to 30 species of Sac Spiders in the Clubionidae family. They are also known as Foliage Spiders and are rather small, often brown or grey spiders. They are not easily identified by just looking at them or from a picture, for most are almost unmarked. Sac spiders are nocturnal hunters. During the day and in winter they will retreat under bark, stones or in a rolled up leaf. Here they make a firm web near the surface. Between web and surface there is just enough room for the spider to be relatively safe in. The overwintering Sac Spider below can not be named from just a few pictures, so we'll stick to Clubiona sp.
