Isopropyl alcohol, also known as rubbing alcohol, is perhaps a surprising item for an orchid enthusiast to have on hand. And yes, you’re right, it isn’t good for your plant, exactly...except if you’re having a problem with scale or mealy bugs.
Identify and Treat Scale Quickly
Scale and mealy bugs come from the same big insect family as aphids. They can all be detrimental to the healthy Phalaenopsis orchid, but scale especially can spread quickly through a greenhouse or home environment, so it is very important to identify and treat it quickly and thoroughly.
You won’t want to soak your plant in isopropyl alcohol, since it would dehydrate it, but if you use a cotton swab or dilute it in a spray to directly treat the pests, it will help you get rid of pests that threaten the health of your Phalaenopsis orchid.
It may require more time and attention to pinpoint your target, but it is effective and safe for use indoors. You will want to make sure you reach every area that might be affected. Being thorough early on will help you not only save your plant, but keep you from having to do repeated treatments.
For difficult cases, you may need to try it in combination with insecticidal soap, horticultural oil or chemicals to defeat these pests.
Also, be sure to clean off any garden tools that you may have used on infected plants with the rubbing alcohol. Otherwise, you may merely be spreading them around instead of eradicating the threat. Hopefully, with some care, you won’t have to sacrifice even one plant to save your collection.