Fungus Gnats: Cannabis Garden Pests
Fungus Gnats: Cannabis Garden Pests
Fungus Gnats are small, fruit fly-sized, insects that typically affect indoor plants These pests are attracted to the moisture of soil and adult gnats will lay their eggs near the surface.
Their life cycle is shorter and eggs typically hatch after about three days. Once the larvae have emerged from their eggs, they burrow further into 
the soil and begin to feed on any present fungi and decaying plant material. About two weeks later adult gnats will emerge from the soil. These adult gnats will repeat the reproduction process, living only about one week. When a heavy presences of these pests begins to take over your plant, larvae will feed on the plants roots.
These pests are very small and resemble a fruit fly in size, and their larvae are even smaller. Fungus Gnats can be either grey or black and have long legs and antennas that give them a smaller mosquito-like appearance. Their larvae have small, black heads with a thin white or translucent bodies.
Signs of Fungus Gnats
Fungus Gnats spend most of their time on the surface of potted soil and flying through the outer edges of the pot or near drainage holes. These pests are not strong fliers and usually only fly short periods of times, opting to walk around when able. Their flight pattern reflects one of a mosquito, rather than a fruit fly, despite the size.
Cannabis roots are not the first choice food for the larvae of these pests. Fungus Gnat larvae will choose the fungi and decaying matter within the soil first. Adult gnats are harmless to plants in the sense of damage, as damage only occurs when the fungus and decayed materials in the soil are depleted. When the roots of a cannabis plant are compromised during development, it can affect a plants ability to uptake the necessary water and nutrients. This causes wilting and even stunted growth to the affected plant.
Indirect damage caused by feeding larvae can also introduce infections and diseases to the plant through wounds. The damage caused can vary due to:
- Plant Age
- Plant Size
- The Number of Larvae Present During Feeding
Prevention Tips and Tricks
- Water management will help lessen problems with Fungus Gnats. This controls water accumulation within the soil and lessen the chance of algae spawning. A dry surface is less attractive to the adult female gnat.
- Research sprays and powders for the soil to eliminate eggs and larvae from damaging the plant due to lack of matter in the soil.
- Sticky Traps for Adult Gnats and using potato chunks to attract larvae.
- Intensely researched noninvasive predators for the gnats and larvae. If you choose this route, please do heavy research – as importing invasive species, of any kind, to your area can be extremely harmful to the environment. This is recommended for the more experienced gardener and should not be the first step taken.
- Shop with our “pest resistance” tag online or instore for an additional layer of defense.