This reminds me that I need to find a source for 10x-20x magnifiers that people can use to look for mites on the bottoms of leaves. Unless you see live ones moving about it is very hard to diagnose mites with any certainty.
Charlie
I was at the mall yesterday and there's a store that sells loupes. I got a bit of sticker-shock, they were charging $50 for a tiny 20x loupe. The glass was maybe, if I'm generous, 1cm diameter. Needless to say I didn't buy it.
Brookstone had a big 10x lighted magnifier for $20. It may be a bit too big to get into tight areas close to the stem, but if you only want to inspect the underside of leaves it works great
http://www.brookstone.com/sl/product/64667-big-10x-lighted-magnifier.html