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Fungus Gnats

Fungus gnats are small, dark flies that hover around houseplant soil. While adults are mostly a nuisance, larvae can damage roots in large numbers.

Causes possibles

Consistently Moist Soil

Why: Fungus gnat larvae feed on organic matter and fungi in moist soil. Wet conditions are essential for their lifecycle.

Signs to check: Soil surface stays moist, tiny black flies around the plant, especially when disturbed.

Rich Organic Potting Mix

Why: Soil high in peat or decomposing organic matter provides abundant food for larvae.

Signs to check: Dense, dark potting mix, flies are more numerous in pots with organic-rich soil.

Poor Drainage

Why: Pots that retain excess water keep soil moist longer, creating ideal breeding conditions.

Signs to check: Water takes a long time to drain, pot lacks drainage holes, saucer holds standing water.

Quoi verifier

1
Check if the soil surface stays moist between waterings
2
Count the severity — a few gnats or swarms?
3
Look for tiny white larvae in the top inch of soil
4
Check all nearby potted plants, as gnats can infest multiple pots

Que faire

Let the top 1-2 inches of soil dry out completely between waterings
Place yellow sticky traps near affected plants to catch adult flies
Apply a layer of sand or diatomaceous earth on the soil surface to deter egg-laying
Water from the bottom by placing the pot in a tray of water
For severe cases, drench soil with a dilute hydrogen peroxide solution (1 part 3% H2O2 to 4 parts water)

Quand chercher de l'aide

Seedlings or young plants are wilting despite moist soil (root damage from larvae)
Gnat population is growing despite drying out the soil
Multiple plants throughout the home are affected

Point cle

Fungus gnats are controlled primarily by managing soil moisture. Let the top layer dry out, use sticky traps, and the population will decline.

Suivre la recuperation dans l'app

Enregistrez les progres, configurez des rappels et obtenez un diagnostic par IA.

Telecharger l'app

Sources: NC State Extension, Missouri Botanical Garden. Contenu compile a partir de references horticoles accessibles au public a des fins educatives. Les organisations sources sont listees pour la transparence uniquement et n'impliquent pas d'approbation.

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