Take a soda bottle, clean and cut off the top about 2/3 of the way from the bottom. Dissolve 3 Tbsp sugar in 1/4 cup vinegar, add 1/2 cup water in the bottom of the bottle. Place the cut off top inverted inside the bottom with the screw off top missing. They will go down into the mixture but it will difficult for them to get back out.
https://www.youtube.com/watch?v=IA0DuUdMrRw
Yellow sticky traps.
Take a soda bottle, clean and cut off the top about 2/3 of the way from the bottom. Dissolve 3 Tbsp sugar in 1/4 cup vinegar, add 1/2 cup water in the bottom of the bottle. Place the cut off top inverted inside the bottom with the screw off top missing. They will go down into the mixture but it will difficult for them to get back out.
where are the gnats around plants?? Fungus gnats---- drier plant soil(does not always destroy them completely) adding Nematodes to the soil will kill them; KItchen??Fruit gnats-----remove all sweet stuff fruit,sugery items on counters,alcohol here's a bunch of videos how to make traps for counter tops https://www.youtube.com/results?search_query=diy+fruit+gnat+trap get Nemattack(nematodes) here https://www.arbico-organics.com/category/pest-solver-guide-fungus-gnats
If they are in the house make a mixture of :::
1part Water
1part Apple Cider Vinegar
1part Liquid Dish Soap