There are about 660 different species of spider in the UK, and most of them will never come inside. Each autumn, however, male house spiders come indoors in search of a mate.
In 2013 we recorded sightings from houses around the UK. A free house spider recording app 'Spider in da house' was available through the Android and Apple app stores, and also helps identify the spiders most often seen indoors. We are currently analysing the results.
The large, hairy house spiders commonly seen in the UK belong to the Tegenaria genus.
House spiders in your bath are normally males who are trapped having fallen off the walls while looking for a female to mate with. Females usually stay in their webs, which are often found under the shed, and await a suitor. After a male has found a female's web he will stay with her for a number of weeks, mating with her repeatedly. It is easy to tell the difference between females (above) and males.
The female then overwinters with stored sperm, and the next spring she can produce 10 egg sacs, each containing around 40 to 60 eggs.
Like most spiders, Tegenaria species subdue their prey with venom. The house spider provides a service for home owners, eating flies and other unwanted insects. They are also ecologically important as food for birds and other animals.
Tegenaria house spiders are not the only species found indoors, and other common species include the daddy-long-legs spider, Pholcus phalangioides (which is not to be confused with the daddy long legs or crane fly, a completely harmless type of fly). We have lots of facts about the spiders you encounter.