That is a strange expression, I have had an invasion of gnats in our kitchen.
A quick google search on how to get rid of them gave the answer as Apple cider vinegar in a little dish with some washing up liquid.
we tried it, and what do you know it worked. In the first hour they were flocking to it, and drowning quickly.
since then we have found the source, a bag of lemons and limes got pushed to back of pantry at Christmas time. And disposed of it.
here is a picture of the results