These flies often are fungus gnats and represent a potential thereat to plants. Adult fungus gnats are slender with comparatively long legs and antennae. This stage lives in the soil. Highly organic soils of high moisture content appear to enhance infestations, especially in the presence of decaying plant tissue.
Symptoms first become apparent when plants begin to wilt or develop an unhealthy appearance.
Dark-winged fungus gnat adults are usually noticed before injury caused by the larvae is apparent. All stages can be found in moist, protected areas. Developmental periods depend on temperature. In general, the larvae hatch from eggs about 4 days after being laid. In about 10-140 days the larvae begin to pupate.