There are two species of lace weaver or lace webbed spiders; Amaurobius similis and Amaurobius fenestralis. Whilst the two are very similar we are mainly concerned with A. similis as these tend to be larger and more commonly occur indoors. Lace webbed spiders are very common and widespread throughout the UK, although less so in the far north.
Generally a little smaller than the false widow (Steatoda nobilis) with a body size of up to 12mm the lace weaver spider is often mistaken for the false widow. This is probably due to its roughly similar proportions including a fairly large abdomen in the female. The legs and carapace are also dark brown and glossy, as in most of the false widow spiders (not so reddish though). However, the legs of the lace web are a little shorter and thicker whilst the velvety abdomen is more elongated and not so round as in the false widows. The pattern on the upperside of the abdomen is also not as visible as in S. nobilis and is characterised by three V-shaped markings.
The lace webbed spiders are funnel webs; this does not mean they are associated with the infamous Australian funnel web spiders. It just means they make webs with a flat web with a velcro-like texture which leads into a silken funnel in a crevice. Here the spider waits until an unfortunate invertebrate happens upon the web, at which point the spider darts out and sinks its fangs into the prey.
There have been a few recorded cases of the lace web spider biting humans. Whilst bites were reported as painful the symptoms were restricted to localised swelling for around 12 hours. No systemic conditions were reported and it appears the bite was relatively painless with the following swelling being quite painful.
Although I will be the first to say nature has its own ways, the lace webbed spider exhibits some quite shocking behaviour. The female spider lays around 40 eggs in a protective silk breeding chamber. The mother remains with the eggs protecting them until they hatch at which point, with the mother’s acquiescence, the spiderlings devour her. A process known as matriphagy.