Fungus Gnats or Root Pests in Containers: Soil Replacement Is the Cure

Tiny "Gnat-Like" Root Eaters = Fungus Gnat Larvae

Adults fly (the "gnats" on your Japanese maple); larvae are tiny, translucent worms in soil eating roots and organic matter.

Why Home Remedies Fail

Eggs and pupae are in the soil. Sprays only kill adults. The cycle continues.

The Only Reliable Fix

1. Discard all infested soil—bag and trash.
2. Wash roots gently in lukewarm water to remove soil and larvae.
3. Sterilize pots: Scrub with 10% bleach, rinse well.
4. Repot in fresh, sterile potting mix.
5. Top-dress with ½ inch sand or perlite to deter egg-laying.
6. Use yellow sticky traps for adults.
7. Water with Bti (Mosquito Bits) monthly as prevention.

Prevention

• Don't overwater—let top soil dry.
• Use sterile mix, not garden soil/compost.
• Quarantine new plants 2 weeks.

Japanese maple leaf-eaters are likely different pests (caterpillars, sawflies)—treat separately.