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Have you ever wondered what those irritating Mosquito-like flies are hovering around your indoor plants? They are almost certainly Fungus Gnats. There are several families of flies which are called ‘Fungus Gnats’, but the black Fungus Gnats of the family Sciaridae are the ones you're likely to encounter at home.
Fungus Gnats are also pests in commercial greenhouses and plant nurseries, where they are attracted to potting media, especially media with high moisture and high organic matter content. The adult Fungus Gnats are simply an annoyance, but their larvae breed in potting media and may damage plant roots.
The best way to protect your indoor plants is to prevent adult Fungus Gnats laying eggs in the potting media. Try Yates Gnat Barrier to help control Fungus Gnats in your indoor plants. Yates Gnat Barrier is a natural, non-chemical, physical barrier made from abrasive pumice granules.
The secret to pest control is to keep an eye on your plants so you can spot pest incursions early. For example, you could scan (see Monitor) while you are watering your plants – check for Fungus Gnats flying around your plants, or walking on the potting media surface. For this to work you will need to know what Fungus Gnats look like (see Description), so that you know they are actually Fungus Gnats and not something else.
Prevention is always better than cure. As well as trying Yates Gnat Barrier, there are a couple of other things that you can do to prevent incursions from Fungus Gnats (see How to Prevent Fungus Gnats Appearing).
Regular monitoring of your house plants will ensure that a major infestation of Fungus Gnats doesn’t occur ‘overnight’. Managing Fungus Gnats is much easier if you can catch an infestation in its early stages.
Fungus Gnats are tiny insects that are part of the fly order Diptera. They are somewhat Mosquito-like in appearance and they can be a real nuisance in the home. Major infestations may result in damage to seedlings in greenhouses.
Common Fungus Gnat adults are small, dark mosquito-like flies about 4mm long, with small heads and long legs. They are often seen running on the soil surface. They are weak fliers and tend to just hover around house plants. They have a single pair of wings with a distinct Y-shaped vein at the tips.
Eggs are tiny (0.2 mm), oval, and translucent-whitish, and laid in crevices in the soil surface.
Larvae are pale, translucent, legless maggots, which grow to about 5 – 7 mm in length and have shiny black heads. They are usually found in the top 25 to 50 mm of potting media.
Pupae are brown, about 3 mm long, and found just under the soil surface.
Female Fungus Gnats can lay between 100 and 200 eggs over their short life of about a week. The eggs are laid in the soil, and the larvae hatch and grow through four moults over a period of two weeks. Pupation occurs in a silken chamber near the soil surface. Adults emerge from the pupae about five days later. The entire life-cycle may be completed in about four weeks.
Fungus Gnats are pests of: