The Pot Stickers are butterfly-shaped traps with a sticky material on them. In the photo on their website, they show the trap stuck into the soil of a pot but I ended up hanging mine just above the plants in my little greenhouse just so it wouldn’t get stuck to everything.
The trap worked great, as you can see in my photo, and that was just after a day or two of putting it in place. It at least made me feel like I was making a dent in those annoying insects!
You can read the product details in the link above. They come in packages of 10 for $14.99.
If you do a web search for “sticky traps for fungus gnats” or “sticky traps for whiteflies,” you’ll see other similar products.