Protected by the extremely fine water-repellent hairs covering their bodies, adults and larvae are difficult to drown, and are not affected by contact with most water-borne toxins such as bleach. Boiling water has little or no effect on the adults for the same reason, and even the eggs are highly resistant to both chemical or thermal assault. Eggs can also withstand periods of dehydration. Extermination of this household pest depends on the maintenance of clean household drains for a period of at least three weeks. Suspect drains can be identified by placing a glass jar or taping a clear plastic bag over them, and periodically checking for adult flies. A clear plastic cup coated inside with vegetable oil or
petroleum jelly can also be used. Thorough mechanical cleaning of drains will remove the larval food source, and is the most effective control measure. Alternatively, injected foams containing bacteria or enzymes may be useful to break down gelatinous scum deposits. Besides sink drains, floor drains and shower drains are common sources, as well as leaky shower pans, but any location with moist decaying organic matter can be a breeding site. In commercial buildings,
sump pump pits, sewers, and
elevator pits may trap moisture where drain flies can breed. Because of their attraction to light, drain flies may be monitored by using
fan-based traps baited with visible or
ultraviolet light. However, only killing adult flies is usually not effective; larval food sources must be removed to stop more flies from emerging. ==References==