Autumn, the time of year when leaves are swept from drives, apples are ripe, mushrooms bubble up through lawns and scary, hairy, leggy creatures appear from nowhere to frighten the living daylights out of arachnophobes everywhere. That’s right, the spiders are out to play.
So why is it that spiders are so common this time of year?
Male spiders leave their webs and come out of hiding in autumn in order to mate. This means that the webs you see around and about are more likely to belong to female spiders as the male spiders (ref)
The spiders we find in our homes have not, in fact, “come in from the cold” as is sometimes thought, but are (mostly) different species to those you might find in your garden and are specifically adapted to living inside. The common house spider (Tegenaria domestica), for example, has adapted to poor water and food supplies and to living in an environment with constant temperature and humidity (spider myths link).
Given that houses are a ‘water-poor environment’ and spiders need to drink, one of the most common places to find spiders is in bathrooms struggling to get out of baths or sinks. This is not, as some might think, because the spider has climbed up through the plumbing. In actual fact the spider was probably watching the X-factor with you from under the sofa, when the ad-break came on and it decided to go get a drink from the nearest tap. As baths and sinks are slippery, the poor thing was unable to climb out again.
House spiders I’ve found in my house (smug):
1. Tegenaria duellica, T. saeva and T. domestica– Can be found indoors, or in funnel shaped webs in garages, sheds and outbuildings. T. duellica normally found scurrying suddenly from underneath sofas when you least expect it.
I thought I’d been lucky on my search of the house and not found any lurking in my room until I saw this…
For a list of other species that you might find lurking in your house go here.
Why spiders are excellent:
1. If you have lots in your house you will have significantly fewer flies, moths, mosquitoes and insect larvae.
2. They also eat aphids and other garden insect pests so act as a biological pest control (for free!).
3. By eating these common species of insect, they keep the population numbers down, thereby playing an important part in the ecosystem.
Can you deter spiders?
Basically, no. If spiders are removed from the house, new ones will come in to take their place via cracks under doors, down chimneys, through windows and some can even float in on the breeze on long strands of silk. However some people, (grandmas), swear by conkers as spider deterrents. The chemical in the skin of the conker, triterpenoid saponin, does indeed appear to repel insects such as moths. However various experiments done by the public and the Royal Society of Chemistry show that they are highly unlikely to repel spiders. Although the RSC’s experiment (hilarious video) is rather questionable and involved shoving a conker on a wooden spoon in the spiders face vs. the same treatment with a table tennis ball as a “control”, the children of Roselyon School in Cornwall did some rigorous and much more scientific studies and found that spiders didn’t really seem to mind the presence of conkers (video). However if it gives you arachnophobes peace of mind, go ahead, they look pretty so if they do deter spiders it is a bonus for you.
The Society of Biology are currently doing an autumn spider watch as not much is known about the Tegenaria species. They are collecting data in order to deduce when the spiders start appearing, if it’s the same time all over the uk and whether or not it is related to weather conditions. In order to take part go here.
So, to conclude, if you see a spider in your house, don’t kill it or “put it back outside”, catch it, photograph it and then wave it on its merry way. And maybe leave a towel hanging over the side of the bath during the X-factor.
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