Country diary: Spiders are preparing for their autumn invasion

Langstone, Hampshire: Giant house spiders are elite athletes with the ability to sprint half a metre in under a second

There are six similar-looking species of house spiders in the UK. Countrywide, the most frequently encountered is Tegenaria domestica, the common house spider, but here in the south, it is often outnumbered by the giant house spider, Eratigena atrica (formerly known as Tegenaria gigantia). The females are homebodies, dwelling year-round beneath sofas, behind bookcases, in dusty corners and under-stair cupboards. Their sheet-like cobwebs are ancestral homes, inhabited year after year by successive generations of spiders.

While females rarely stray far from these structures, in a few weeks’ time males will reach maturity and abandon their outdoor webs in search of mates, squeezing into our homes through air vents and open windows. Several months ago, I noticed that a male had taken up residence next to my back door, perhaps in preparation for this autumnal invasion. He’s a prize specimen, with a brown cephalothorax and legs, a hairy, tan and brown herringbone-patterned abdomen, and a pair of swollen, boxing glove-like pedipalps on either side of his head. His messy web is strung between terracotta plant pots but funnels back into a stack of firewood and it’s here that he lies in wait for unwary insects to stumble into the radiating trip lines.

One evening, I was watering my plants and, as water showered his web, the spider dashed out. I assumed that he was responding to vibrations, mistaking droplets bouncing off the silk for struggling prey. Realising there was no meal waiting, he returned to his tubular lair, but as I continued watering he ran out again, repeatedly darting in and out of the spray. With a leg span of up to 75mm, giant house spiders are elite athletes with the ability to sprint half a metre in under a second. His speed made it difficult to focus, but it seemed that he was pausing momentarily before each retreat. Spiders obtain the majority of their fluid intake from their diet. Still, they do drink water – hence often finding them in search of moisture in the sink, shower, or bathtub – and I eventually deduced that the arachnid was pausing to dip his straw-like mouthparts into the droplets and suck up the thirst-quenching fluid.

Country diary is on Twitter at @gdncountrydiary