Moth flies in buildings feed primarily inside drain pipes and do not damage plumbing. Although larvae of these species may feed on plant roots outdoors, none causes serious damage outside the home. Any root feeding by these species in gardens or landscapes is usually minor in comparison with their beneficial role as decomposers, helping to convert dead vegetation into nutrients for plant growth. If you are unable to determine what kind you have, identifications can often be obtained from samples taken to county Cooperative Extension offices, agricultural agencies, university entomology departments, or at some well-staffed nurseries and garden supply stores. Adult fungus gnats have slender legs with long segmented antennae, longer than their head.
Females lay tiny eggs in moist organic debris or potting soil.
They eat organic mulch, leaf mold, grass clippings, compost, root hairs, and fungi. Antennae are bristlelike, shorter than the head, and not obvious. Their wings are dark, with five light spots. Shore flies are stronger, faster fliers than fungus gnats, but they have less of a tendency to take flight in comparison with the more easily disturbed fungus gnats. Larvae have no distinct head capsule, but their dark mouthparts and internal organs may be visible through their outer skin.