I have an article about research that showed diluted soybean oil works well for spider mites. If anyone wants to try it I'll look up the dilution rate.
An article on spider mites, link below, written by entomologists may also be of interest. Note they say oils may be the most effective treatment available to homeowners and that insecticidal soap is only marginally effective.
http://msue.anr.msu.edu/news/s...
Edited to add, diluted soybean oil also works for aphids. I do agree with Elaine though, hot and dry is what spider mites like, they also like leaves that are high in nitrogen.
