Answer: It may be that your orchid is playing host to a colony of mealybugs. These pests like to congregate along stems and on the undersides of leaves. They're hard to eradicate because of the cottony substance that covers their bodies. You can carefully pick the critters off the leaves or dab them with a cotton swab dipped in alcohol. Try not to get too much alcohol on the foliage - it may burn.
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