Fiddle leaf figs are popular houseplants, but can host unwelcome guests. Fungus gnats, small flying insects, are a common nuisance for fiddle leaf fig owners, buzzing around the plant and throughout the home. While generally not harmful to mature plants, a significant infestation can be frustrating and indicates an underlying issue.
Understanding Fiddle Leaf Fig Gnats
The gnats commonly found around fiddle leaf figs are fungus gnats, small, mosquito-like flies. They are about 1/8 inch long, with long legs and antennae, and are weak fliers, often seen near the soil surface or on leaves.
Their life cycle has four stages: egg, larva, pupa, and adult. Females lay tiny eggs in moist soil. These hatch into translucent larvae with black heads, up to 1/4 inch long. Larvae feed on fungi and organic matter, including plant roots, before pupating and emerging as adults. The life cycle takes 17 to 28 days.
Fungus gnats thrive in consistently moist, organic-rich soil. Overwatering is the primary reason for their appearance, as wet soil encourages fungi and decaying organic matter that gnat larvae consume. Damp soil, especially the top few inches, creates a hospitable environment for gnat eggs and larvae.
Preventing Fiddle Leaf Fig Gnats
Preventing fungus gnats starts with managing your fiddle leaf fig’s watering. Allow the top few inches of soil to dry completely between waterings, as gnats cannot lay eggs in dry soil. A moisture meter can help accurately assess soil dryness. Ensure adequate drainage by using pots with drainage holes and a well-draining potting mix. Maintain a clean environment around your plant, free of fallen leaves or decaying organic matter.
When introducing new plants, inspect them thoroughly for pests before bringing them home, and consider quarantining them. Applying a top dressing to the soil creates a physical barrier against adult gnats. A one to two-inch layer of sand or decorative pebbles discourages females from laying eggs in the moist soil below, breaking the gnat life cycle.
Treating Fiddle Leaf Fig Gnat Infestations
Addressing an existing gnat infestation requires a multi-pronged approach targeting both adult gnats and larvae in the soil. First, allow the soil to dry significantly between waterings, impacting larvae survival. Yellow sticky traps near the plant effectively catch adult gnats, reducing the flying population and preventing egg-laying. For a simple trap, combine apple cider vinegar with a few drops of dish soap in a shallow bowl; gnats are attracted to the vinegar and get trapped.
For larvae, use Bacillus thuringiensis israelensis (BTi), a naturally occurring bacterium in products like Mosquito Bits. Mix BTi with water and apply as a soil drench; it targets and kills gnat larvae without harming plants, humans, or pets.
Diatomaceous earth (DE), a fine powder from fossilized algae, can be sprinkled on the soil surface. Its sharp edges dehydrate and kill gnats and larvae on contact, but it loses effectiveness when wet, requiring reapplication after watering.
If the infestation persists, use horticultural oils like neem oil. Mix neem oil with water and a few drops of mild dish soap for an emulsified solution, then apply as a soil drench. Neem oil disrupts the insects’ life cycle and feeding.
Insecticidal soaps are another option, sprayed on the soil surface to kill larvae and adults on contact. Always follow product instructions carefully. For chemical treatments, apply in the evening or move the plant to a shady location to prevent leaf damage from sun exposure.