Fungal Gnats

• Adult fungal gnats cause little damage to plants; however, they may become a nuisance to gardeners when they fly around in the home. Female fungus gnats lay eggs within the first 2 to 3 inches of top soil. When eggs hatch, larvae eat the decaying organic matter in potting medium and plant roots. Gardeners may see larvae after placing a piece of potato in the surface of the soil. Larvae push their way through the soil to the potato and begin feeding. Identifying larvae is important, because pests cause numerous health problems for prayer plants.
  
  

Damage

• Fungal gnat larvae eat away at the root system, which disrupts nutrient and moisture flow. The result is foliage that turns yellow, wilts or falls off the prayer plant. In addition, gardeners often take stem cuttings from their prayer plants to grow new plants. Larvae prevent these cuttings from developing proper root systems. Because female fungus gnats lay up to 300 eggs, gardeners may see a rapid health decline in their prayer plant as the pest population skyrockets.
  
  

Control Methods

• Remove your prayer plant from its container. Mix up new soil that is half potting soil and half peat moss. Use sterilized potting soil and not dirt from your yard. Yard dirt may contain harmful pathogens or pests that may hurt your prayer plant. Avoid overwatering your prayer plants. However, prayer plants must have moist soil to prevent their leaves from drying out. Allow the first 2 to 3 inches of soil to dry out in between waterings.
  
  

Chemical Methods

• Treat adult fungus gnats with a pyrethroid-based insecticide. Choose an insecticide that has active ingredients such as bifenthrin, cyfluthrin and permethrin. Use a soil drench to treat fungus gnat larvae. Pick a soil drench that contains Bacillus thuringiensis subspecies israelensis. Bacillus thuringiensis subspecies israelensis works by producing a toxin that kills off fungus larvae. Furthermore, granule insecticides that contain imidacloprid will also kill fungus larvae. Keep the prayer plant away from children and pets when treating with insecticide.