House spider

House spider - Tegenaria species

Overall size: up to 120mm

Season: These spiders are usually seen in the autumn months when males leave their webs in search of females. They frequently enter homes through open windows, chimneys or gaps beneath doors.

A large spider with a brown cephalothorax (the fused head and thorax) and a tan-coloured abdomen that often has a characteristic ‘herring bone’ pattern. Six species of this group are commonly found in homes, and you may often find them in the bath or dashing across the living room floor.

They range in size from the relatively small Tegenaria domestica to the quite large Tegenaria parietina, which can reach a leg span of 120mm (5 inches) in the adult male.

Their sheet-like webs are usually built in garages, sheds, loft spaces and cavity walls. They are less likely to be full time occupants of our living areas due to disturbance.

Distribution and habitat

Most of our species of Tegenaria were probably introduced into this country during the last few centuries among imported cargoes from the Mediterranean Region. The natural habitat of the spiders includes caves and hollow trees but, of course, they readily adapt to buildings.

In Britain, Tegenaria house spiders are still in the process of expanding their range in the north of England and Scotland. Before long, few locations where there are houses will remain free of them.

Webs and life cycle

House spiders build cobwebs consisting of a silken sheet which funnels into a retreat at the back. These are permanent structures which can attain considerable size (and dustiness!) in an undisturbed cellar, shed or garage.

Young spiders (resembling small versions of the adults) hatch from the egg sac and grow to maturity within a year. Males, when they become adult, are distinguished by the sex organs on the ends of the palps which look rather like a pair of boxing gloves. The males usually die in the autumn soon after mating, but many females survive to the next year, during which they produce a number of egg-sacs.

Control of house spiders

In this country many millions of people are bothered by the presence of Tegenaria house spiders. While these spiders are most numerous in outbuildings, such as garages or sheds, they move around at night (especially August to October) and enter living rooms through open windows and gaps around doors.

As yet, nobody has invented an effective device to deter spiders. The remedy is to prevent their entry by closing windows and blocking gaps with the use of plaster, draught excluders and insect screens for doors and windows.