Spray a thin coating of metaldehyde spray onto the orchid to exterminate the insects. Alternatively, mix 1 teaspoon canola oil, 1 teaspoon dish-washing liquid soap and 1 cup water in a spray bottle to spray the damaged plant.
Pour rubbing alcohol on the pruning shears to disinfect the blades, and wipe down the blades with a soft cloth.
Clip the damaged leaf to the section where the leaf is healthy. A clean cut eliminates the dead, damaged part of the leaf and prevents spreading of disease.
Wash the pruning shears in the sink and pour rubbing alcohol onto the blades to disinfect the shears from disease. Wipe the blades dry with the cleaning cloth.
Spray the metaldehyde or homemade insecticide once a week to eliminate all aphids without harming the orchid.