Sciarid flies
damage is the immediate result of larvae feeding on the roots. The larvae feed mainly on decaying plant material and on algae and fungi present in the soil [...] Damage symptoms The larvae of sciarid flies feed mainly on organic remains and the fungi that grow on them, although some species can also eat living plant [...] They, however, can also feed on root hairs, rootlets, and tender root, stem and leaf tissue. Later instars may even feed on plant stems. The injuries caused