I brought some spider plants to work. Now we have little black flies.

Mostly likely fungus gnats. They will have to be re-potted in fresh soil. Fungus gnats lay eggs in the soil,spraying alone with not get rid of them

Try two or three tablespoons of cider vinegar with a drop or two of Dawn dish soap and a teaspoon of honey. Mix well. Form a paper tunnel. Put mix in a glass. Top with tunnel out of mixture, prop along side. Flies will go in but not get out because of the tunnel. Kind of like the Asian beetle traps. Did this twice when I brought plants in and bugs gone. Good luck! They might be similar to what we call a fruit fly. The eggs are in the dirt and hatch when you bring plants in. Outside birds etc eat the tasty little things so you do not see them.

They might be fungus knats. They lay their eggs in damp soil. The best thing to do is let the top layer of soil dry out - nowhere to lay eggs!

I learned from my grand mother to use egg shells.. u just sit them right side up in the soil works great ;)

Try a drop is soap in your water, won't hurt plants.

They are gnats, just spray plant and soil with a little dish liquid and water, should do the trick.