Fungus gnats are a common nuisance for indoor plant enthusiasts, particularly those caring for money trees. While generally more of an annoyance than a severe threat, their presence indicates problematic environmental conditions. Addressing a gnat infestation not only restores peace to your home but also promotes a healthier growing environment for your money tree.
Identifying Money Tree Gnats
Fungus gnats often appear as small, dark, mosquito-like insects, about 1/8 inch long. They are weak flyers, usually seen hovering around the soil surface or crawling on nearby surfaces, especially when disturbed or watered. Their erratic flight pattern helps distinguish them from other flying insects.
Fungus gnat larvae reside within the soil. They are tiny, translucent white worms with distinct black heads, up to 1/4 inch long. These larvae may be observed in the topsoil. Signs of their presence include yellowing or wilting leaves, resulting from larvae feeding on roots in severe infestations.
Why Money Trees Attract Gnats
Money trees attract fungus gnats due to care practices creating an ideal breeding ground. Overwatering is a leading cause, as consistently moist topsoil provides an ideal environment for gnat eggs and larvae. Gnats are drawn to damp soil where fungi, a food source, can grow.
Potting mix type also contributes to gnat infestations. Rich, organic mixes retain moisture, offering a hospitable environment and food source for larvae. Poor drainage, leading to water accumulation, exacerbates moisture retention and creates stagnant conditions gnats favor.
Eradicating Money Tree Gnats
Controlling gnat infestations involves a multi-pronged approach targeting adult gnats and larvae. Yellow sticky traps effectively capture adult gnats, as they are strongly attracted to yellow. Placing these traps near the plant reduces the adult population, breaking their reproductive cycle. An apple cider vinegar trap (apple cider vinegar, sugar, dish soap in a shallow container) is another simple adult control method.
Several treatments can address larvae in the soil. Bacillus thuringiensis israelensis (BTI) is a naturally occurring bacterium that specifically targets and kills fungus gnat larvae without harming other organisms, including plants, pets, or humans. BTI, found in products like Mosquito Bits, is used by soaking 4 tablespoons in one gallon of water for 30 minutes, then watering the plant’s soil. This treatment should be repeated weekly for three weeks to ensure all larvae are eliminated through their life cycle.
Hydrogen peroxide kills gnat larvae on contact in the soil. Mix one part 3% hydrogen peroxide with four parts water and water the soil. The solution fizzes, destroying larvae and eggs. This treatment can be repeated weekly as needed.
Neem oil, from the neem tree, repels and disrupts various pests, including fungus gnats. Dilute 1-2 teaspoons of neem oil with a quart of lukewarm water and a few drops of mild liquid soap, then apply to soil and foliage. For severe infestations, repotting with fresh, sterile potting mix removes a large portion of gnats and their eggs.
Preventing Future Gnat Infestations
Long-term prevention adjusts environmental conditions to deter gnats. Proper watering is paramount; allow the top 1-2 inches of soil to dry completely before re-watering. This deprives larvae of the moist environment they need. Bottom watering, where the pot absorbs water from below, also keeps topsoil drier, discouraging gnat egg-laying.
A well-draining potting mix is important for prevention. Money trees thrive in soil allowing excess water to escape, preventing waterlogging. Mixes with peat moss, perlite, coarse sand, or coco coir provide good aeration and drainage. Adequate drainage holes are essential to prevent water pooling, which can lead to root rot and a damp gnat environment.
Good air circulation around the money tree helps the soil surface dry quickly, deterring gnats. Avoid standing water in saucers, as this provides another breeding ground. Regularly remove dead leaves or debris from the soil surface to eliminate gnat larvae food sources. Always inspect new plants for pests, including fungus gnats, before introducing them to your home to prevent infestations.