Fruit flies
Red eyes, with a tan front and a black rear. They breed in fermenting food, empty bottles and cans, bins and drains, not in the compost of the pot.
Symptom
Gnats in houseplants
The short answer
Small dark flies drifting up from a pot are usually fungus gnats, and the adults you are swatting are not the problem: they neither bite nor damage the plant. The larvae in the wet top layer of compost are, and the first thing to change is how you water, letting the top of the compost dry out between waterings, before anything needs to be applied.
- Fungus gnatBradysia spp.Most likelyWeak, erratic fliers that stay near the pot and rest on or run across the compost surface. Press a slice of raw potato into the compost and lift it after a day or two: translucent, legless larvae with shiny black heads gather underneath.Full pest profile →
- Shore fliesScatella spp.Less oftenStouter and stronger, faster fliers than a fungus gnat, with very short antennae and pale spots on dark wings. Mostly a greenhouse fly: the larvae feed on algae on wet benches and compost rather than on roots, but adults have been shown to carry root-rot pathogens to healthy seedlings.Full pest profile →
macro · adult on compost surface
At a glance
- Profiled here
- 2 pests
- Also consider
- 3 other causes
- Leave alone
- 1 of them is harmless
When it is none of those
The rest of what gets called “gnats in plants”. Some are pests we have not profiled yet; some are insects doing you a favour; some are not insects at all, and no treatment will help.
Drain flies
Small, delicate and fuzzy, pale brownish-grey to black, and found mostly in kitchens, bathrooms and basements near drains. The larvae live in the slime inside drains and traps, but they can also breed in water left standing in saucers under pots, so empty those too.
Rove beetles
A slender beetle on the compost, with short wing cases and most of its abdomen bare, is a rove beetle. It hunts fungus gnat larvae rather than breeding among them.
Rove beetles →Still not sure?
Four questions about the damage separate these better than an appearance can, and this page answers some of them for you.
Setting · indoorsWhere · roots or soil line
Continue to the picker