Brown Bumps on Orchid Blooms and Leaves: Scale Insects—Control with Horticultural Oil

Identification

Brown, hard bumps on Phalaenopsis flowers and leaves that scrape off but return, plus sticky honeydew = scale insects. Adults are immobile under protective shells.

Treatment

1. Lightweight horticultural oil (summer oil): Spray entire plant, including visible roots. Avoid open blooms (oil causes wilting).
2. Repeat weekly until bumps slough off easily (dead scale).
3. Alternative: Q-tips + rubbing alcohol for manual removal on small infestations.
4. Fertilize lightly to support recovery.

Why Oil Works

Oil smothers scale through their shell. Systemic insecticides are less reliable on hard scale. Ants farm scale for honeydew—control scale to deter ants.