Fungus Gnats on Dieffenbachia: Not Aphids

Fungus Gnats on Dieffenbachia: Not Aphids

The tiny black flies are fungus gnats, not aphids. Larvae live in damp soil with decaying organic matter. Soapy sprays won’t reach them.

Eradication

1. Remove all loose surface soil (where larvae concentrate).
2. Let soil dry several inches deep before watering.
3. Sprinkle thin sand layer—sharp edges kill larvae.
4. Adults die in ~1 week.

Keep soil dry; population will crash without chemicals.