Sciarid flies
species are mainly found in commercial mushroom cultivation where they can cause enormous damage. Sciarid flies are usually found in damp, humid environments [...] commonly in greenhouses throughout the world. Although they generally do little harm to healthy plants, sciarid flies are particularly problematic in cuttings [...] feed mainly on decaying plant material and on algae and fungi present in the soil. They, however, can also feed on root hairs, rootlets, and tender root