COLOR: Black, brown or yellow
Inside, gnat infestations are almost always associated with the soil of overwatered potted plants. Secondarily, consider signs of water leaks or moisture problems. Outside, mulched areas and the soil associated with them is usually the source. Especially if new mulch is added annually without removing the old first.
Look for moist areas which will support fungal growth. Once area is found either remove or dry out the moist material.
Spring, Summer, Fall & Winter