ARACHNIDA > ARANEAE > Amaurobiidae

The Amaurobiidae family includes just three species in a single genus, Amaurobius.

Their webs are a tangled mesh of closely woven threads surrounding a circular retreat typically leading into a crevice on a vertical surface. When freshly spun, the threads have a lace-like appearance with a bluish tinge.

Laceweb spiders are eight-eyed, fairly large and robust, with swollen chelicerae which are often visible from above. The front of the cephalothorax is broad and rounded with a slightly raised and parallel-sided head region that is darker than the rest of the carapace. The abdomen has characteristic dark wedge-shaped markings.

The largest and darkest species is Amaurobius ferox known as the Black Lace-weaver. It is the least common of the three species, but still well recorded particularly across central and southern counties.

Amaurobius fenestralis and Amaurobius similis are said to be extremely similar in appearance requiring microscopic examination for reliable identification. However, their preferred habitats are quite different as Amaurobius fenestralis is found under the bark of trees, under stones and in dense vegetation such as gorse, and is not generally associated with gardens or buildings, whereas Amaurobius similis is typically found on buildings where it spins its web around holes in walls or on window frames.

I have to admit that I struggled with identification of the individuals featured here as, to my eyes, the overall appearance and colour bears little resemblance to the photos in my field guide. Fortunately, I was able to get them checked out and confirmed on the FB British Spiders Identification Group, so I know they're correct. I questioned the fact that they didn't look much like the dark specimens shown in the book and was given the advice to accept that spiders in general are quite variable and that in this case the shape of the pattern is the important identifier.

The late season individual labelled as Amaurobius cf.ferox is immature so a degree of caution is needed.

Updated, Jan.25 (v3)