Houseplants add appeal to any home decor and most are easy to maintain. However, insect infestations can threaten the health of the plant and become a nuisance for the homeowner. Fungus gnats are pests that live in the potting soil of houseplants. Houseplants infested with fungus gnats can often be identified by fungus gnat larvae that is visible in potting soil.
Adult fungus gnats are approximately 1/10 to 1/8 inch in length and resemble dainty mosquitoes. Fungus gnats place very tiny, transparent eggs in the potting soil of houseplants. The gnat larvae hatch from these eggs and are small, white grub-like worms. The larvae lives in the potting soil and feeds on the decaying matter in the soil. Adult fungus gnats only live for seven to 10 days, but females can lay 100 to 300 eggs in potting soil during this time.
Fungus gnats are often first noticed when homeowners move or bump the plant, causing the gnats to swarm. This pest is also attracted to well lit areas and is often found flying in windowsills near houseplants. Fungus gnats are not extremely damaging to plant health, but they can damage plant roots if infestations are heavy. Symptoms of root damage from fungus gnat feeding include plant wilting, slow growth, leaf yellowing, reduced vigour and premature leaf loss.
Inspect your plants after purchase for signs of fungus gnat infestation, before placing them inside your home. Place your plants in sterile potting soil to prevent fungus gnat infestation. Avoid overwatering your plant since fungus gnats are attracted to moisture. Houseplants that are taken outdoors must be inspected for fungus gnats before bringing them back into your home. Be sure to keep your yard and garden free from plant tissue and debris, as this promotes fungus gnat development.
Chemical control products are available at your local garden centre for fungus gnats. Purchase a product labelled for flying insects or gnats for best results. Repeat applications of insecticides for continued pest control. Yellow sticky traps will help capture fungus gnats when placed just above infested plants. Houseplants with very heavy infestations of fungus gnats may need to be discarded if these control efforts fail.