Splendid spiders

I’ve never been the biggest fan of spiders. As a child I would call my dad to remove any that chanced inside my bedroom, and the sight of one scurrying across the floor was enough to induce a stomach-clenching shiver. Over the years, and probably resulting from my burgeoning interest in animal behaviour, I got braver: in my first house share at university I was the one who would take a pen and gently prod the offending creature into a glass for humane eviction. Since then, having moved past the initial distraction of fear, I’ve been able to actually watch spiders, and I’ve realised they are fascinating little animals.

The last couple of years, I’ve noticed them more. Especially in autumn. I’m sure that spiders are not becoming more numerous, but it certainly feels like it. One recent sunny mid-September day, I went outside and within five minutes spotted no fewer than 12 plump female garden spiders sitting in the middle of beautiful large orb webs. The majority were around our Rose of Sharon bush, which was still in flower and therefore still attracting insects. Approximately half the spiders were feeding on something: I spotted a wasp, shield bug, ladybird, and numerous small flies neatly bundled up in silk. Sometimes I’d get too close and the spider would flee into the surrounding foliage, straight down one of the radial silk strands that gives the orb its characteristic bicycle wheel shape.

If you’re not sure which is the garden spider, it is almost certainly the one you’ve noticed in your own garden or park. Among the most common and well-known of our arachnids, they are varying shades of pale yellow, rust orange, brown and black, with stripy legs and a characteristic white cross on the abdomen. They are industrious night workers, spinning complex vertical orb webs (up to 40 cm across) in preparation for a day of sitting and catching prey.

Autumn is a busy time for garden spiders. They’ve been growing all summer and they’re getting broody. The males face particular risks: not only must they find females and convince them to mate, they must also avoid becoming their dinner. Sexual cannibalism is a well-known phenomenon in the spider world, and while we’ve all heard of southern hemisphere black widow females feasting on male suitors, it’s perhaps less known that it could be happening right in your garden too! The problem is that spiders have very poor eyesight, so they rely on vibrations in their webs for information about the world around them; be that a prey item, predator or mate. Orb spiders like the garden spider do this from the centre of their web, which is remarkably well optimised to transmit vibrations.

To get to the female the male must make contact with her web, so the first challenge is to convince the female, who is up to twice his size, that the vibrations he is creating do not signal a meal. He does this by attaching a silk line to the female’s web, and spending hours plucking at it to coax the female off her web – she is less dangerous when she can only move forwards and backwards. The whole routine may take a day, involving a series of advances and retreats from the male until the female has accepted him or is too tired to attack. Sometimes it doesn’t pay off, and the female – tired and hungry – eats him anyway.

But if he can get close enough the male steps things up a gear and starts to show off his moves. In sudden bursts he rushes in and uses his front legs to drum rapid rhythms on the female’s legs and abdomen, retreating to continue plucking at the web (I videoed this – which my friends think is weird – but you can see here and here). Once accepted, he comes right up to the female and seemingly bites her in her abdomen, but in fact he is transferring sperm using a pair of short leg-like structures on his head called pedipalps. Afterwards, he bids a hasty retreat: she may have approved him to father her offspring but that doesn’t mean he can’t also be a nutritious snack.

Once mated, the female isolates herself for several days and builds an egg sack – a tightly spun silken cocoon in which she lays hundreds of eggs – under leaves or in rocky crevices. Her work is done, and after a couple of days she dies. The eggs lie dormant over winter but hatch the following spring, and hundreds of tiny yellow spiderlings begin their lives, ballooning away to pastures new on long strands of wind-caught silk. The cycle starts over again.

I’ve had a sneaky glimpse into the spider’s world and have transitioned firmly into a fan. They are essential animals, keeping the insect population in check, and most of the time they want as little to do with us as we do with them. For the garden spider, the next generation is already developing in safe silk cocoons, but as autumn advances and the weather cools, other spiders will venture forth and seek warmth from our homes. The annual house spider invasion will occur, and when it does, I for one will try and ensure safe passage.

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