Gnats in houseplants

(Question)

My indoor snake plant has been infested with knats. I have tried several natural suggestions, the latest a neam oil solution. It is quite large, but I removed the interior pot only to discover the knats escaping from the bottom. I also placed yellow paper covered Iin vaseline around the base ; they are outwitting me. Help? Thanks. P.S. should I remove the soil and place plant in a bucket of water?

(Answer)

Thanks for contacting Toronto Master Gardeners. Those gnats can be quite annoying! Fungus gnats are usually harmless but they can damage the roots of some plants. They look a little like small mosquitoes and tend to appear when a plant has been overwatered and decaying plant matter litters the area. The best way to avoid fungus gnats is to water plants deeply and allow them to drain thoroughly. The top two inches of potting mix should dry out between watering. All plant pots should have a drainage hole and the water that drains into the saucer below should be removed.
You can remove the plant and repot it in gnat free soil. When you remove the plant from the infected soil, wash all of the soil off the roots of the plant. Then wash the container with a weak solution of bleach water. This will kill any eggs or larva still in the pot. Repot the plant in fresh soil and allow the soil to dry out in-between watering to prevent re-infestation of gnats
Some other strategies you might try include the following:
Predatory nematodes: It works best to soak the soil before applying the microscopic worms. Nematodes are applied as a soil drench when temperatures are between 15 to 32 degrees Celsius.
Bacillus thuringiensis subspecies israelensis: Add the beneficial bacteria Bacillus thuringiensis subspecies israelensis (Bti) to the soil.

For more information on getting rid of gnats please refer to the following sites:
https://homeguides.sfgate.com/kill-fungus-gnats-houseplants-dish-soap-87288.html

https://www.gardeningknowhow.com/plant-problems/pests/insects/fungus-gnats.htm