Fungus gnats, also known as Scarid Fly, are one of the most crop devastating insect pest that any indoor grower is likely to encounter, equally as bad as spider mite.

They can be even worse than spider mites because they do their damage well hidden amongst the roots. At least with spider mites, provided you are watching your crop, you can spot them as soon as they appear.

However, the first sign of Fungus Gnat is usually an abundance of small 3-5mm long flies on the surface of the root ball or medium in which the plants are growing and by this stage the plant will be suffering. Each Fungus Gnat female lays 200 eggs in warm conditions.

The eggs hatch out into maggots which immediately start eating the plant’s roots. These maggots, although they are small, are eating machines.

They munch their way through the root system quicker than the plant can grow new roots. They damage the plant’s ability to take up water and nutrients.

The damage they cause also exposes the plant to root diseases. In short, they can totally wreck the plant’s root system without you being aware of what’s going on amongst the roots. When the plant’s root system is wrecked, so is your crop.

The maggots will become adults in two weeks and lay their own batch of 200 eggs per female.

That’s 20,000 maggots eating roots in just 4 weeks or two generations. DON’T WAIT UNTIL YOU SEE ADULT FLIES BEFORE YOU START TREATMENT. Do what the label says (and what commercial growers do) and use Nilnat as a preventative.

That’s when it is most effective. If you see small black flies walking around the surface of the medium, you should be immediately suspect of Fungus Gnats.

They generally prefer to walk around but they will fly when disturbed. If you suspect damage, look for the larvae amongst the roots.

These larvae are tiny but conspicuous. They have clear white or yellow bodies and black heads. Plant symptoms are generally those of various nutrient deficiencies. Root diseases, such as Pythium, use the damage caused to the roots by the Fungus Gnat maggots as an entry point.

Canadian Xpress Nilnat is a biological control for Fungus Gnats. It is a microscopic crystal which, when eaten by the Scarid Fly maggots, swells up in its gut, perforates the gut wall and kills the maggot. Even though you use Nilnat, you may still see an occasional Fungus Gnat-don’t be alarmed. The Nilnat will be working. Remember that the maggots must first eat the Nilnat for it to be effective. It doesn’t kill the adults. The adult flies may still enter your growing area from other sources. In fact, Fungus Gnats have become a serious problem in nurseries and indoor growing areas all around the world. They, therefore, are numerous wherever it is warm enough and wherever there is moisture and food. That’s a lot of places that will support a Fungus Gnat population and provide a source of infestation for your growing area. We also recommend keeping your growing area dry and free of dead leaves, bits of soil, etc.