Potting soil
Best fungus gnat traps
The best fungus gnat trap is a yellow sticky card in the plant, used as a census, while you let the soil dry. Fungus gnat larvae feed in damp mix. A card that fills every day means the pot is still a bog. Bti granules labeled for fungus gnats hit larvae in soil you cannot dump. They do not forgive daily overwatering.
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Best monitor: Yellow sticky insect cards. Yellow cards at soil level catch adults. Keep the sticky face off pets and curtains. Replace a coated card. The count should fall after the soil surface dries between waterings.
Compare the picks
| Role | Tool | Best for | Type |
|---|---|---|---|
| Best monitor | Yellow sticky insect cards | Houseplants and seed trays | Hardware |
| Best larval treatment | Mosquito Bits (Bti granules) | Soil you have to keep | Labeled product |
| Best way to stop overwatering | Pin-type wood moisture meter | Pots you kill with kindness | Hardware |
Which one to buy
Hardware
Yellow sticky insect cards
Best monitor — Yellow cards at soil level catch adults. Keep the sticky face off pets and curtains. Replace a coated card. The count should fall after the soil surface dries between waterings.
Labeled product
Mosquito Bits (Bti granules)
Best larval treatment — Bti granules labeled for fungus gnats or as mosquito bits used as that label allows in pots. This is a larvicide, not a reason to keep the saucer full of water.
Hardware
Pin-type wood moisture meter
Best way to stop overwatering — A meter, or just a finger in the mix, beats another card. Decorative pots with no drainage are a factory. Repot those.
The trap falls when the soil dries
Let the top inch dry. Empty saucers. Quarantine a new nursery plant before it joins the shelf. Sticky cards alone are a scoreboard. If you water on a schedule instead of by dryness, you will buy cards forever.
Common questions
Do yellow sticky traps get rid of fungus gnats?
They catch adults. Larvae in wet soil keep emerging. Dry the mix and, if needed, use a labeled Bti product.
Are fungus gnats fruit flies?
No. Fungus gnats come off plants. Fruit flies come off fermenting food. The traps are different. A vinegar jar will not fix a wet pot.
Is Bti safe in houseplant soil?
Use a product whose label lists that site. Mosquito Bits are a Bti granule people use for gnats when the label allows. Follow the rate. Do not invent a dunk-in-the-pot recipe that the label does not describe.