Fungus Gnats on Jade Plant: Source, Treatment, Prevention

Carol repotted her jade 3–4 months ago. Now tiny black flies hover over plant, furniture, walls – spreading through house.

Identification: Fungus Gnats

Likely introduced with new potting soil. Adults are annoying but harmless; larvae in top soil layer feed on decaying organic matter.

Treatment

1. Remove added soil, keep original rootball intact, repot in same/similar pot. (Jades rarely need repotting.)
2. Dry soil thoroughly – jades need dry conditions.
3. Surface barrier: Coarse coir, sand, diatomaceous earth, or fine peat moss on soil surface to kill larvae.
4. Potato slices: ½-inch raw potato slices on soil overnight attract larvae; discard daily until clear.
5. Knock-Out Gnats (Gardens Alive) for serious infestations.

Prevention

• Sterile, bark-free potting mix with perlite/sand for drainage.
• Avoid overwatering – #1 cause of fungus gnats.
• Red wine traps for adults.

Detection trick: Add water, watch for tiny larvae swimming in surface pools.