Funny you mention spiders as Robert Bruce talks about them in his book practical psychic self defense. He says a lot of these parasitical entitys are spiders, but he also says he you can kill them through visualisation techniques. Ive also read a few aya reports and people see the ayahuasca ridding themselves of these astral parasites. I seen a spider like thing on mushrooms once just for a moment but it was hovering right at me I think you are probably right eliyahu when talking about silencing the thoughts as Robert Bruce talks about this in his book, good read though a bit far and freaky lol find it funny though I read that book years ago and the same storys pop up here and there. http://www.amazon.co.uk/Practical-Psychic-Self-defense-Understanding-Influences/dp/1571742212