They thrive in moist soil and humidity indoors. The information I found was : Spray a mist of soapy water in your summerhouse clean, seal any cracks and then keep ventilated. The breeding ground may be your planters? Get rid of the contents and clean treat if needed too. Hopefully they are not in your soil?

I've not heard of springtails before, what are they ?

They're incredibly numerous tiny insect-like animals.

According to Wikipedia -
"In sheer numbers, they are reputed to be one of the most abundant of all macroscopic animals, with estimates of 100,000 individuals per cubic meter of topsoil, essentially everywhere on Earth where soil and related habitats (moss cushions, fallen wood, grass tufts, ant and termite nests) occur." They can creep slowly around, but their most noticeable form of locomotion is using their "spring tail" - they jump.

Your chances of eradicating them are nil, and why would you want to? They feed on detritus, moulds, bacteria and so on and like damp environments like the compost round plants.

Just ignore them, they're not doing any harm.

Are you certain they're springtails? These tiny creatures are rarely seen in the UK, although present in great numbers in the soil and in woodlands. and unless your walls are wet, I can't imagine why they'd be there.

I've seen them on walls occasionally, we used to live in a cottage with walls made of cob (basically mounded earth with horsehair) and sometimes had them indoors. They didn't do anything except lurk.

Blimey, you must have really good eyesight, Beattie - I'd notice, say, earwigs or silverfish, but springtails, unless they were in a vast heaving mass, would probably remain invisible to me.

Perhaps they were an extra large species Bamboo - they were almost 1cm long.
Or maybe I mis-identified them? Will Google....

Well, this just goes to show that you shouldn't ALWAYS believe everything your mother tells you....
Thanks to Google and an online insect identifying key I have just discovered that the insects I've always thought were springtails are, in fact, jumping bristletails!!
http://biokeys.berkeley.edu/inverts/archaeognatha.html

:-) You learn something every day!

I think if you had Springtails you would want to reduce/eradicate them Beattie as the are in vast numbers. But I must admit I thought this was a non British question - my mistake.

Thanks guys, sadly I have good eyesight and can sport them and they are springtails even tho they tend to be a USA problem. I would not mind them if they stuck to the garden but a friend of mind lived in a very damp house once and she had millions of them living in there with her and I'm worried this may happen to me. Also they are breeding in abundance in my grandson's sandpit and this makes me feel uncomfortable.
I am going to try some earth-friendly washing up liquid and clean out my planters and after washing round the summerhouse I'll probably varnish it inside and I'm praying this will help. The sand will have to be thrown away though until the problem can be sorted out. I wouldn't mind but I can only find one animal that eats them and it's a particular frog... I'm digging a pond just in case lol :)