There is a difference between red spider mites and red spiders. The mite ones live on plant-life and they spin webs on the plants, which is mentioned on those garden web-sites (pardon the pun!) But.. you've got no plant life? Yours are red spiders. Just google red spiders, they're a real nuisance this time of year. They get inside if you're not careful. If they get inside a building, they live in cracks (brickwork, round windows, skirting boards etc.) They breed from April - July/Aug. They love to climb up things... walls, windows etc. But you need to focus on where they are breeding which will be lower down. Ant powder and ant spray works, but don't breath it in! Or I used anti-bacterial spray (for kitchens, worktops etc) aimed at the cracks. Boiling water works too. Check walls, paths, paving slabs OUTSIDE your doors & windows cos they may be breeding there instead of indoors. Again, boil the kettle and pour water on (but be careful) Hope it works!