For years, a popular gardening hack has circulated among houseplant enthusiasts: sprinkling crushed eggshells on soil to repel pesky fungus gnats. The theory suggests the sharp edges deter these tiny insects from laying eggs. But does this home remedy actually work?
Experts now say the evidence is clear: eggshells have no significant effect on fungus gnat behavior. These insects are attracted to moist, organic-rich soil, not repelled by calcium carbonate fragments. The shells may even retain moisture, potentially worsening the problem.
"Fungus gnats don't care about eggshells," explains entomologist Dr. Lisa Chen. "Their primary concern is finding damp soil where they can lay eggs near fungal food sources for their larvae."
Instead of relying on ineffective home remedies, gardeners should focus on proven control methods. Letting soil dry between waterings, using yellow sticky traps, and applying biological controls like Bacillus thuringiensis israelensis (BTI) are far more effective strategies.
While eggshells can provide calcium to plants when composted properly, their reputation as a gnat deterrent appears to be more folklore than fact. For those battling these persistent pests, science-backed solutions offer better results than kitchen scraps.