Common Name:Sewer Flies
Sewer flies are very common in the vicinity sewage , block drains, stagnant pool or ponds of water. They will irritate workers and nearby inhabitants by fling into the eyes, mouth and nostrils, resting on wall inside your homes, shop restaurant as they are being disturb by workmen. they breed on the fungi, algae, bacteria and sludge that makes up the biological layer present on the surface of sewage percolating filter beds Relative slow breeding flies there maybe about 8 generation a year with serious outbreaks in the summer months
Biology : The female will lay up to 100 eggs either in singles or in a small groups at various depth on the biological matter or filter bed. The eggs are about 0.2mm long, white and oval in shape. Eggs development takes 1-6 days and larval development from 10 days at 25°C to 50 days at 7°C. The total life cycle ranges from 16 to 140 days within the same temperature but completion of the life cycle will not happen below 6 °C.
Control : there is no simple way of prevention sewer fly outbreak even by suitable management of the sewer filters. The application of insecticides directly to the filter beds could not only result in potentially damaging release of chemicals into the waterways but also upset the balance of organism within the biological film that provides the natural breakdown of the sewage within the filtering system . However a Bacillus Thuringiensis product is cleared for used for fly control on biological filters in waste water treatment works. control is restricted to targeted application of pyrethrins or synthetic pyrethroids knock -down sprays, or surface treatment of premethrin on fly resting areas away from the filter beds.