Unfortunately, these are impossible to see until after they have done damage. So you do want to treat for several weeks. Then observe. If you see any of that characteristic silvering on anything, jump back in to the treatment program. Persistence and eternal vigilance pay off.
Invest in a 5X loop. Will cost about $10-15. Might even be able to find one cheap on ebay.
Its invaluable in spotting little critters on your plants. I find it works best if you hold the plant in bright light when checking.
Judi
Agreed! Also you can wipe the underside of any leaf with a barely damp white paper towel. Mites leave a tell tale rust colored smudge on the paper towel.
When I suspect mites I do basically what bethmarie explained. I do it with a white cotton embeded in a solution of 5% alcohol.
If it comes sort of red/brown then it's mites.
Unfortunately it's almost impossible to eliminate them 10%. Once you get them, your expectations must be to keep their population under control and not exterminate them all.
This is all great info ya'll. Thank you so much! So if I continually keep their numbers under control, should I be worried about my other plants getting mites as well? Are they more likely to attack plants with thicker leaves (like phals) or are they not picky? I also have several oncidium types and paphs and don't want them to get these nasty things too.
Mites like warm, dry weather with low humidity. Spraying your plants with water regularly knocks them off the plants, and they can't crawl far enough to get back aboard.
Across the gardening universe, some plants are known to be spider mite magnets. In the orchid world these would be Phalaenopsis, thin-leafed Oncidiums and hybrids, Cymbidiums, and especially the various species and hybrids in the Catasetinae tribe.
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