As autumn sets in, many people who suffer from arachnophobia find themselves on edge, checking shadowy corners, peering into the bath, and cautiously lifting pillows before getting into bed. This time of year marks what is often called Spider Season, when most of Britain’s 650 spider species reach maturity and become more visible as we go about our daily routines.
You might spot a garden orb spider suspended at the centre of a web stretched across your path, a long-legged cellar spider bobbing in the garage when the light flicks on, or a glossy false widow tucked away in a tangled kitchen web. But the spiders that most often spark panic are the large, fast moving Common House Spiders that appear indoors throughout autumn.
Belonging to the genus Tegenaria, these spiders can span up to three inches across and are among the quickest runners in Britain. Contrary to popular belief, most house spiders do not invade from outside. They have likely spent their entire lives within our homes. Hidden away under wardrobes or behind furniture, they quietly grow for up to two years, feeding on small invertebrates that stray too close.
So why do they suddenly appear in autumn? It is not a mass invasion. It is the males on the move. Mature males leave their webs to search for receptive females to mate with. Once he finds her, the male performs a delicate courtship ritual before transferring sperm via specialised appendages known as 'palps'. If he is lucky enough to avoid becoming her next meal, he will crawl away and die, leaving the fertilised female to rest through the winter within her silken retreat.
When spring arrives, the female awakens and spins silken sacs for her eggs, hanging them amongst her web before she too dies. Around six weeks later, about fifty tiny spiderlings emerge through a pin sized hole and disperse to find new hiding spots within the home. Over the next two years, the survivors will mature into the next generation of large, hairy house spiders that reappear each autumn, much to the dismay of arachnophobes everywhere.
Did You Know?
House spiders play an important role in keeping homes free from other pests by feeding on insects and small invertebrates. So, next time one scuttles across the floor, remember it is more helpful than harmful.
Discover more fascinating insights from Dr Ian Bedford in our ongoing Bug of the Month series, exclusive to Fargro Home and Garden.
About Dr Ian Bedford
Ian has been fascinated by the bug world for as long as he can remember. From studying butterflies on the South Downs as a youngster, he went on to pursue a career in Research Entomology and ran the Entomology Dept at the John Innes Centre in Norwich up until his recent retirement.
'Bug of the Month'
Visit our 'bug of the month' archive.
Every month Ian will share his knowledge on how to protect your plants and gardens from preventable pest invasions while providing valuable insights into the insects regularly found in our gardens.