Tiny bugs flying around my cannabis plants – fungus gnats?

There are tiny black flies buzzing around the soil surface of my plants. They're really small and seem to hang out near the top of the soil. I think they might be fungus gnats? Are they harmful? How do I get rid of them? My plants are 3 weeks into flower.

3 comments

3 Comments

Experienced1mo ago

Pro tip: add a layer of sand or perlite on top of your soil. Gnats can't lay eggs through it. Works as prevention for future grows too.

Experienced1mo ago

Fungus gnats! The adults are harmless but their larvae eat roots. **Quick fixes:** 1. Let soil dry out more between waterings (larvae need moisture) 2. Top-dress with diatomaceous earth (kills larvae on contact) 3. Yellow sticky traps to catch adults 4. Water with Mosquito Bits tea (BTi bacteria, kills larvae) The BTi treatment is the most effective long-term solution. One application usually handles it within a week.

Experienced1mo ago

I had gnats in flower too. The sticky traps + letting soil dry out fixed it in about 10 days. Your buds won't be affected — the gnats are only interested in the soil.