Hello!

Just wondered why I am putting between 3 and 8 very large spiders (diameter 40-80mm) out of my house nearly every night since April?
my friends think it's the same ones & they find their way back in again. We were tempted to mark each one with a spot before putting it out just to see.....will it harm it??
If they haven't got a built in  "homing" device, is it unusual to have this many out & about so early in the year, I thought they didn't go on the run until they were looking for a mate??
Also, we wondered if there is anything we can do to deter them, my wife and son aren't spider fans and I'm getting fed up with the banshee-like shrieks! :rolleyes:

Thanks!

I don't think marking some of them should harm them, especially if you mark the body rather than the head. It would be interesting to know though....... If you do mark them, I would be interested to know whether they are the same ones or not.

However, my expectations would be that the spiders would be different, and that they hatched somewhere around your house (or even within it, especially if you have a basement) and that there is a constant supply. I had the same happen to me, although including a different group of arachnids, when I lived in Oslo. We had hundreds of Opiliones (harvestmen or 'daddy long legs') invading our house. My brother and I used to kill them so the supply of these were certainly replenished. We found out in the end that they came from a pile of firewood just below my bedroom window.

However, I know of no way to get rid of them if there is a constant supply. However, if there are around 8 of them that keep reentering your house, you could get rid of these individuals pretty easily, either by 'you know how' or a more humane way, take them far away from your house before releasing them.

We did not get rid of the harvestmen until the autumn (but it was not any priority for us to get rid of them).

Last edited by Eric Tetlie (25th May 2007 16:59:35)

Hi mark,

Glad you are asking a question about this. In general, I fully agree with eric, but i would add that alot of the answers depend on what kind of spiders they are, ie. are they ground running (something like one called Tegenaria) or do they hang around the ceiling sitting and waiting (something like Pholcus).

Regardless, I also think it is quite likely many of these spiders are coming from inside your house, but maybe your wife and son shouldn't hear this. For peace of mind, i suggest you look for cracks and gaps round windows and places like that - to see where they might come in, then close those potential entry points. Don't block up air bricks though, if you have those, they are important for preventing damp in your house, and in case of gas leaks!

It is difficult to say why you get more spiders since April, some spiders have egg sacs over winter, that hatch in spring. In those types, the baby spiders are now big enough to be noticed by April.

I also go with Eric about running an experiment on the spiders, and involving your son if possible. You can mark the captured spiders with tippex/white-out (name depending on your nationality), best on the second-rear segment [the abdomen], or better yet somewhere high up on the legs, near the body. (the lower parts of the legs nearer the foot have lots of hairs the spiders use to sense the world, and you dont want to damage those). Tippex is not toxic for insects like beetles, so my guess is that it is fine for spiders too. Maybe try marking a captive one, keeping it well fed, and in a container with lots of air holes. I think the only dangerous thing about using tippex may be the gas fumes as it dries.

Now, if you mark several spiders differently, you can release them at different distances from the house and see if any return, and/or how long it takes. This is a good way to get your son to do a science experiment, and hopefully get him to stop disliking spiders so much.

In general, most spiders seem to have a very poor sense of direction, but there are some tarantulas that migrate in America, in the same direction each year. However, most spider explorations seem to be quite random, unless they already have a trail marked in silk. If spiders are entering your house by a favoured route, this trail will be marked in silk :)    Again whether it is just boys or boys and girl spiders roaming around all depends on the type of spider. For some, you are right that just males wander around looking for mates, but in other types, both sexes actively hunt and wander around.

Finally, i do not agree with Eric about getting rid of the spiders by 'you know how'. (sorry Eric). In fact, spiders are great predators, and should be released in the garden to eat the flower/vegetable pest insects.