Dear Readers, a spider has been spinning a new web outside my kitchen window every day for the past few weeks, and I haven’t given it much heed. When the sun sets, it’s lit up for twenty minutes, and so I pay it a little more attention then. And then I noticed something. If you look very closely (and ignore my dirty window, ahem) you’ll see that at about 11 o’clock there’s a whole sector missing.

And this got me very excited, because it means that the web was made by none other than the missing-sector orb spider (Zygiella x-notata). This is actually an abundant and widespread spider, so you might have some in your vicinity too – they usually spin their webs in the upper corners of windows, so this one is behaving exactly as the textbooks predict. Furthermore, when young the spiders make a new web every single night, which is why when I look for the web during the day I can’t see it – the spiders either eat or cut the web loose and then remake it. During the day, the spider itself lives in a retreat, usually in the window frame, but at night they appear at the centre of the web. I saw the owner of this web last night, and although I couldn’t get a photo, I was surprised at how small it was, and how shiny.

Missing Sector Orb Web Spider (Photo By Dariusz Kowalczyk, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=74486272)

The back of the spider is coated in a chemical called guanine, which is the same as the stuff that makes fish scales shiny. In fish, this might help to disguise them from predators in the shifting light of the upper ocean, but who knows why a spider sparkles? I love that the abdomen looks like a little leaf too.

Why, though, does the web have a missing sector?

Better photo of a web with a missing sector (Photo by By Andreas Eichler, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=45149922)

Well, during the day as we know the spider hides away out of sight, but there is a single strand that runs through the missing sector and into the spider’s refuge. The spider sits with her front legs on the sector and the slightest vibration will see her running into the web to catch her prey. She can do this very quickly as she’s just running on a single thread, rather than having to find her way through the complicated structure of the web itself. You could say that the missing sector is a design improvement, developed over literally millions of years. Interestingly, the less food there is to be had, the larger the web that the spider spins. However, Missing Sector Orb Spiders are also capable of building ‘proper’ orb webs if the location isn’t suitable for a missing sector (say, where the sector would be obscured or the angle is wrong), so it’s clear that these animals are far from being little robots, incapable of adjusting their behaviour when things change.

Missing Sector Orb Spider in her refuge (Photo Dariusz Kowalczyk, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0&gt;, via Wikimedia Commons)

So, I was absolutely delighted to see this new-to-me spider, and I’d be willing to bet that if you’re in the UK you have a good chance of finding one too. The only downside is that my windows, already home to a laceweaver at the front, some noble false widow spiders in the kitchen and now a missing sector orb spider at the back, are even less likely to be cleaned in the near future. I think my induction into full-on cronedom, with a bunch of froggy, spidery, buggy familiars, is getting every closer ever day. Bring it on!