fungus gnats on Alocasia
Quick answer
If your Alocasia has fungus gnats, the most likely cause is: Fungus gnats are small 3-4 mm flies that hover above damp Alocasia substrate and lay their eggs in the top layer of moist compost, where the larvae feed on fungus and decaying organic matter rather than on the established plant itself; populations tend to escalate when the substrate stays constantly wet, when organic fertilizer is over-applied, or when the top of the pot never dries out between waterings because each of those conditions raises the fungal load that sustains the larvae.
Start here:
- 1. Allow the top of the Alocasia substrate to dry out between waterings so the upper layer that the adult gnats use for egg-laying stops being a suitable breeding site, and bottom-water the pot only when the weight of the pot shows that the lower compost is also drying through.
- 2. Switch from a heavy organic mix to a chunky, well-draining aroid substrate and cut back on natural fertilizer applications to remove the fungal food that sustains the gnat larvae through their underground maggot stage.
Why Alocasia gets fungus gnats
Alocasia spp.
Fungus gnats are small 3-4 mm flies that hover above damp Alocasia substrate and lay their eggs in the top layer of moist compost, where the larvae feed on fungus and decaying organic matter rather than on the established plant itself; populations tend to escalate when the substrate stays constantly wet, when organic fertilizer is over-applied, or when the top of the pot never dries out between waterings because each of those conditions raises the fungal load that sustains the larvae.
How to reverse fungus gnats on Alocasia
- 1
Allow the top of the Alocasia substrate to dry out between waterings so the upper layer that the adult gnats use for egg-laying stops being a suitable breeding site, and bottom-water the pot only when the weight of the pot shows that the lower compost is also drying through.
- 2
Switch from a heavy organic mix to a chunky, well-draining aroid substrate and cut back on natural fertilizer applications to remove the fungal food that sustains the gnat larvae through their underground maggot stage.
- 3
Cover the surface of the Alocasia pot with a thin layer of coarse top-dressing such as grit or LECA so adult flies cannot easily reach the damp compost to deposit their eggs.
Keep fungus gnats off this Alocasia
Use a free-draining chunky aroid substrate, water only when the top of the mix begins to dry, and avoid letting water collect in decorative outer pots so the surface of the Alocasia's substrate never stays damp enough for the gnat eggs to hatch into maggots.