Fungus Gnats

Gnats are those small flying insects that resemble mosquitoes in looks, but the former are smaller in size. These insects have a short lifespan of around two to four weeks. But, within this time, they may prove harmful for your plants. Apart from that, flying gnats can be a nuisance inside the house.

Houseplants and Fungus Gnats

So, fungus gnats are insects that can damage houseplants. The name is derived from their love for fungi. These insects are found to feed on fungi, organic material in soil and young roots of plants. They can be equally harmful to both indoor and outdoor plants. It is the larvae of fungus gnats that are responsible for feeding on the young roots and seedlings of plants. The adult insects are often found to fly around, and are considered as a nuisance. While, flying fungus gnats in your garden or around houseplants is a sign of their presence, you may also notice yellowing and wilting of leaves. This is caused by the gnat larvae that feeds on the young roots of the plants thereby depriving them of sufficient nutrition. They may also act as vectors of plant diseases, as they fly from one plant to another. Before starting with control measures, you must identify the insect, so as to confirm that the problem is caused by these insects only.

Identifying Fungus Gnats
They are small flying insects with gray or black, body color. These are similar to mosquitoes in size, but are smaller with a body length of around two five millimeters. They are delicate-looking insects with gray-colored wings that have Y-shaped markings. The wings are almost translucent and the antennae as well as legs are long and slender. They feed on fungi, plant waste and organic materials in soil. Fungus gnats love moist soil, in which eggs are laid by females.

Lifespan
They have a short lifespan, which consists of four stages - eggs, larvae, pupa and adult insects. The eggs are laid as strings on the superficial layers of the medium, which is mostly moist soil or peat moss. The eggs hatch within 4 to 6 days and the emerging fungus gnat larvae have cream-colored bodies with black head capsules. Their body length may be around five millimeters. They feed on the root hair of plants and seedlings, for around two weeks. After that, they pupate and within 4 to 6 days, adults emerge. These insects are poor fliers, but most of them are found to be females and this explains their rising population. The adults live for around 7 to 10 days only. So, in short, their lifespan is very short and may range between two to four weeks.

Fungus Gnat Control
As they can cause damage to plants and nuisance in the house, fungus gnats have to be controlled as soon as you notice them in your house, garden or greenhouse. It has been observed that over watering is one of the common causes for fungus gnat infestation, as these pests love moist soil. Certain potting mediums, like peat moss also attract these insects. It has also been noted that soil with aged compost may also become a breeding ground for these insects, as they feed on decaying organic matter. If you opt for organic measures, you may use bacteria called Bacillus thuringiensis var. israelensis. Even parasitic nematodes and predatory mites are found to be effective in controlling these pests. You may also use yellow sticky traps for trapping adult gnats.

In short, getting rid of fungus gnats is not a difficult task, as you can obtain the necessary materials from the local nursery or garden store. You may also seek the help of a horticulturist for some guidance. However, prevention is always better to avoid infestation. This can be done by avoiding over watering and by controlling fungal infections.