Fungus Gnat - Neoempheria

Gnats are a general term for a lot of small biting bugs. Some gnats will eat plants and other insects, but others eat certain breeds of fungus

If you notice little gnats flying out of your potting soil every time you water your houseplants or container garden, you have a problem with fungus gnats. 

While these small bugs can seem insignificant, they can be an irritation if you have plants indoors. 

Meanwhile, the gnats' underground maggots may start to feed on your plants' roots, causing damage and plant stress. 

Gnats generally appear in your houseplants and container gardens due to potting soil contamination and unclean gardening tools, which can hide gnat larvae and gnat eggs.

Always use sterile potting mix -- if you're using garden soil, bake it at 250 degrees Fahrenheit for 30 minutes to sterilize it -- and rinse all pots and garden tools in a solution of 1 part bleach and 9 parts water.


http://homeguides.sfgate.com/remove-gnats-potting-soil-44258.html
https://www.peststrategies.com/pest-guides/gnat-guides/do-gnats-bite/