Kensizer 20-Pack Fruit Fly Trap, Yellow Sticky Gnat Traps Killer for Indoor/Outdoor Flying Plant Insect Like Fungus Gnats, Whiteflies, Aphids, Leaf Miners - 6x8 in, Twist Ties Included

Yellow sticky gnat traps (there are many brands): https://www.amazon.com/Kensizer-20-Pack-Dual-Sided-Whiteflies-Insects/dp/B07KRRJT5J There are ones to stake and ones you can hang, either one works. Also, just cut them to whatever size you need.