Home gardeners living in central Florida are certainly used to dealing with challenges when it comes to raising plants. Hot temperatures, drought conditions and periods of wet weather all can cause problems in your plants, especially during the late summer months.
Insect infestations are common in our area this time of year. Although some insects are damaging to your plants, many are simply a nuisance when populations are high. Fungus gnats are common pests in central Florida, living inside your houseplants and your outdoor garden plants.
Adult fungus gnats are slender flies that look more like mosquitoes than house flies. Females typically live seven days and lay eggs in batches in the soil of outdoor gardens and houseplants.
Although adult fungus gnats do not feed on your plants or damage them, they can be a nuisance when present in large numbers.
These gnats are usually seen swarming indoors near windows, where light is abundant after emerging from the soil of potted plants. Fungus gnat adults emerge from slender, white larvae living in the soil of potted plants or in wet outdoor soil.
The larvae survive by feeding on organic matter in the soil, as well as decaying plant roots. Immature plants and young seedlings are at the greatest risk of damage by fungus gnat larvae. Plants with roots damaged by the larvae become more susceptible to root diseases that can cause them to experience reduced vigor and eventual death.
Although fungus gnat populations are highest during the summer when rain is frequent, there are some things you can do to reduce their populations in your garden and on your houseplants.
Because fungus gnat larvae thrive in wet soil, avoid overwatering your plants to keep them at bay.
Placing sterile potting soil in your house plants will reduce fungus gnat development, as these pests feed on decaying organic matter.
Healthy plants are less likely to have insect infestations, so be sure to take good care of your plants to reduce insect populations. If you follow good sanitation and plant care practices, it will greatly reduce the likelihood of fungus gnat infestations on indoor plants.
When you purchase new houseplants, always quarantine them for 7 to 10 days before bringing them inside your home. This way, you can catch fungus gnat infestations before they spread to your other plants. Many houseplants have fungus gnats present, even when no larvae or adult forms are visible at the time of purchase.
If you have fungus gnats, you will most likely see adults swarming near doorways, windows or directly over potted plants. Adult fungus gnats can be captured by placing yellow sticky traps around your home where you most often see flies swarming.
You also can see the larvae of these pests in the potting soil of infested houseplants.
Most fungus gnat larvae live in the first two inches of potting soil. Predatory mites and parasitic wasps both feed on immature fungus gnat larvae and may help control populations. These natural predatory insects will not attack fungus gnats in their adult form.
Pesticides may be necessary if you have large populations of fungus gnats. There are a variety of products available at your local garden center that can be applied as a soil drench or sprayed on the foliage of infested plants. Always follow the directions on the manufactures label for best results.
Finally, if you cannot seem to eliminate indoor fungus gnats, it may be necessary to discard all infested houseplants. Although this may seem drastic, it is often the only way to reduce indoor infestations and keep other houseplants free from insects.