— The adult black gnats fly around the plant but do no damage. The immature larvae in the moist soil can chew plant roots. They are often a problem in overwatered plants or overly moist flats of seedlings.
Moth Flies- These flies look like 1/4 inch long black moths and are found in areas near floor drains. Often in basements, commercial bathrooms, utility rooms etc. that have floor drains. They breed in the detritus at the water line in the drain and emerge when the drain gets dry. These are eliminated by drain treatments.