Yellow sticky traps for fungus gnats
Written by Mustafa Ayan Fact-checked against university extension/IPM sources Last reviewed: October 14, 2026
Direct answer
Yellow sticky traps catch adult fungus gnats and show whether your treatment is working, but they don't end an infestation alone because larvae in the soil keep producing new adults. Lay or stand cards at soil level, replace them when full, and watch whether the catch trends down over several days.
What traps do well
Adult fungus gnats are weak fliers and are drawn to yellow. A sticky card at soil level intercepts females before they lay the next round of eggs. You also get a visible count, which is the only honest way to know if the infestation is shrinking.
Placement that works
Cut larger cards into strips. Push them into the mix so the yellow face sits just above the soil, not up in the foliage. One card per small pot; two for a large planter. Keep them out of reach of pets and kids — they are extremely sticky.
Replace cards when they are covered or dusty. A full card stops catching. Check every couple of days during week one.
The limit
Traps do not kill eggs or larvae in the soil. If you only trap adults, larvae keep pupating and the cloud returns. Pair traps with managed moisture and, if that's not enough, a labeled Bti product — hydrogen peroxide is an optional, more cautious add-on, not an equal alternative.