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Loads of spiders living under decking at back door. Any way to discourage them without harming them?

My wife has a pretty severe spider phobia. We got 2m x 4m decking installed in our garden late last summer and in recent weeks have noticed lots of small-ish spiders popping up onto the decking from underneath. It's not a swarming mass or anything but at any one time there could be around 3-5 of them on the decking so I imagine there are a fair few more underneath. The decking is built right up to our back door so my wife fears them coming into the house en masse.

The spiders are about the diameter of a 20p piece at the minute and tend to scatter and go under the deck as soon as you go outside. I don't mind them being there and know they are clean and prey on other bugs that can spread illness, but due to my wife's fears I'd like to find a way to encourage them to move elsewhere. I absolutely will not harm them though so anything lethal / toxic is not an option.

I tried some peppermint oil I bought online but it hasn't seemed to make any difference so far. I did some reading and also saw some pieces that suggested they'll move on in the coming weeks anyway, so not sure the best approach. Any ideas welcome, thanks!


  • I need this solution too, when I cut the grass they disperse in swarms 
  • Woolsery
    Woolsery Posts: 1,535 Forumite
    First Post Photogenic Name Dropper
    I don't think these are gardening matters just because they happen out of doors; they're wildlife related.

    If spiders are living in a lawn and that's a problem, then the only practical solution is to replace the lawn with an environment hostile to spiders. The lawn gives them cover from predators and potential food sources, whereas an open, flat surface doesn't.
    Similarly, any structure with dark internal spaces, like decking, will provide refuge for insects and spiders. Place it next to the house and they'll take up residence. There isn't any long term solution to minibeasts living under sheds, decking or anything large placed in the garden; it's what they do.
  • I managed to get my daughter to be less spider-phobic by gradual exposure - looking at pictures, looking at them from a distance, etc - it's a recognised technique for phobias in general (though my approach was just at an amateur level). Might be better to focus on the phobia rather than the spiders - which your wife is likely to encounter elsewhere anyhow. Plus, they obviously love the decking as a home, so unlikely to want to move into the house without all those nice hidey-holes... :)
  • Woolsery
    Woolsery Posts: 1,535 Forumite
    First Post Photogenic Name Dropper
    edited 28 April 2022 at 8:36AM
    It's when the rodents make homes under decking that the fun really starts, but they don't tell you that in B&Q!
    Always a good idea to leave a cat or terrier-sized hole somewhere.....Even better, get a ferret. They're great. :D
  • twopenny
    twopenny Posts: 5,545 Forumite
    Name Dropper First Post First Anniversary Photogenic
    It's a fact that insects, probably arachnids too, don't like strong smells. 
    Cirtonella has been the longest standing soloution. You could try multiple cottonwool balls soaked in a soloution of almond oil and some drops of citronella oil.
    Cedar works too. Used to be used as cedar wood boxes to store fabrics against insects.
    I used to plant lavender outside the kitchen window to stop flies coming in. You could wipe lavender around the door frame. It's easy to make lavender water around the door frame. Grow lavender around the deck.
    These sound like the ones I have in my garden that run fast. They don't get any bigger aand have never come inside. They are definitely outdoors only.
    Then seal the deck of every hole. 
    Spiders usually only come in in the early autumn (no need to tell the wife) to mate. They then go out to lay eggs.

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