A GIANT BRITISH SPIDER

This is the giant house spider (close-up of head and palps on the left) Eratigena atrica (C. L. Koch, 1843)[1]. They are quite common and this one had been living in our house for a while before it died, hopefully, and probably, after mating. They are not dangerous and, although they will bite if molested, it won’t harm you or your pets as the bite does not normally pierce the skin. Even if it did, the effect of the spider’s poison (an agatoxin) is not dangerous to humans and only causes slight redness/minor local swelling/itchiness. I have been bitten by one when moving it (I thought gently!) out of the way. It was just a little nip.

This specimen has a body length of 16mm with a leg span of 8cm. The females are even larger. Males and females are similar but males, like this one, usually live outside until late summer when they enter houses looking for a mate. The females stay indoors permanently and build webs in out-of-the-way places such as behind cupboards or in the loft or cellar space. They can also be found in sheds and outhouses but they dislike the cold. The web has a funnel in which the female hides, ready to pounce on any prey (flies and other small insects/arthropods) passing by.

Giant house spiders are found in Europe and increasingly worldwide, presumably spreading with humans. Females produce sixty or more spiderlings, emerging from an egg sack, which stay in or near the nest for a month or so. Cannibalism occurs if food is scarce. They go through several moults before reaching adulthood.

Unfortunately, many people have a fear of spiders, sometimes developing into full-blown arachnophobia. As well as being big, this species moves very quickly, but there is really nothing to be frightened of, rather there is much to be fascinated by.

Betts Ecology work to conserve spiders and other invertebrates. Please help us by not killing these useful, ecologically valuable and fascinating animals.

Photos © Betts Ecology

[1] The nomenclature is rather confused and this species has now been split into three by the taxonomists. There is also the very similar domestic house spider Tegenaria domestica (Clerck, 1757)