Two spiders in the bath - only one came out alive

Cellar spiders Pholcus phalangioides look fragile, with those long, slender legs, but they are formidable hunters. This is what happened when a house spider climbed down into our bath, to drink from a dripping tap, and became trapped. The cellar spider climbed down after it, snared it with silk, bit and paralysed it, then wrapped up its prey in a silken shroud.

The cellar spider had little difficulty in climbing out, with its prey slung under its body, then spent the rest of the day clinging to the skirting board, guarding its meal from rival spiders.

These lanky, harmless arachnids need warmth and are confined to human dwellings in Britain. In 1958 the eminent arachnologist W.S. Bristowe, in his book The World of Spiders, described how he zig-zagged across England on his motorcycle, requesting to see hotel rooms on the pretext that he might rent them, so that he could check for the presence of Pholcus and map its distribution. He only found it along a narrow corridor in southern England.

Since then this synanthropic spider has moved north – perhaps in furniture removal lorries, because it seems to have a predilection for living behind settees and under tables – and has even reached the Shetland islands.

The spider season

 There are some fascinating spiders around at this time of the year. This little beauty is a zebra spider, that lives in my greenhouse. It doesn't make a web, it leaps on its prey. The forward-facing pair of its eight eyes are especially large, giving it binocular forward vision and the ability to judge distance accurately.

The garden spider below has spun its web in my greenhouse, across the doorway: I have to duck under it to get in and out. I watched as it caught this wasp and wrapped it in a silken shroud in less that 20 seconds. In the second picture you can see the prey's jaws protruding through the silk, as it tried to bite its way out - unsuccessfully.

This house spider, below, had fallen into our bath - probably entering the bathroom through an open window after climbing up the outside wall. It most likely fell in when it tried to drink from the dripping tap. It's now re-housed in the greenhouse.

House spiders look fearsome but they are easy prey for cellar spiders that trap them in their silken threads, using their long legs to drape the thread around their prey, then paralysing it with venom. They guard their captured prey, usually taking a couple of days to eat them, leaving only a few pieces of its exoskeleton. 

Both cellar spiders and crane flies are commonly known as daddy-long-legs but when the two meet (below) the outcome is never in doubt. Most crane flies that find their way into our house end up in a cellar spider's web.

Cellar spider catches a woodlouse (arachnophobes look away now)

 

The cellar spider Pholcus phalangioides is a welcome guest in our house. In summer it's a very effective fly killerand it also catches and eats much larger spiders, of the kind that sometimes turn up in the bath or race across the ceiling and floor when the cold weather brings them indoors, in autumn. A few cobwebs in corners of the ceilings are a small price to pay for these services.

Sometimes these spiders catch woodlice, which is what this one has trapped in its web, alongside a fly that has already been encased in silk. But this woodlouse was a prize catch, because its a female that was carrying baby woodlice, known as mancas, in its brood pouch, under those armoured plates. They are the tiny translucent woodlice, as yet with no hardened armour, that you can see in the photograph below.

Female woodlice carry their young in a brood pouch under their body, and at this stage the young only have six pairs of legs. After their first moult they develop an extra body segment and after the second moult they grow an additional pair of legs, so they are then classified as juveniles with the full adult complement of seven pairs of legs.

For a closer look at woodlice, check out my Beyond the Human Eye blog here.