Then a soap solution probably won't help as much. I wonder if you have your trees in a dullish and dampish environment, as that's often what spiders like, but you may just have to be a little more aggressive about dealing with them ("heavy' chemicals are not always necessary) if you want to keep your trees free of them.

well i live in toledo it used to be all marsh land so damp may be an understatement however i do live on the second floor and i have an overhang built for my trees to rest on so there sitting is not nessesarily damp and as far as dull goes they get about 3-4 hrs of direct sunlight and recieve all day light as well.

My first bonsai gifted to me before I knew nothing about them. It was a juniper and I noticed little webs on it and when I looked closer I saw little spiders. I was like neat microspiders. It wasn't till months later I figured out the microspiders were tree mites and not so cute. The tree was since dead =)

If they aren't parasites and you don't have prey for them inside they will probably go away on their own.

hooks:

Try using plain rubbing alcohol (or 409 or Fantastik, or their generic equivalent) on the plant (Spritz it on the leaves and stems). Make sure to water the plant thoroughly as the treatment is slightly drying to the plant, (and thoroughly drying to many insects). It works on ants, and spider mites, mealy bugs etc - so it may work on spiders too.

Most 'bug sprays' available for home use are made using pyrethrins - which occur in, or are derived from chemicals that occur in, chrysanthemums, and do not contain active 'heavy chemicals' per se [by which I'm assuming that you mean they are made somehow only from a barrel of 'heavy' crude oil].

Please check out the article on natural carcinogens you are exposed to in a holiday dinner below. The main point is: just because it's manmade doesn't mean it's toxic, and just because it's natural doesn't mean it's safe.

Here is a link that might be useful: Carcinogens in a Holiday Dinner