Fruit & Filter Flies (Drosophila spp. & Psychoda sp.)
The adult fruit flies are very small insects, about 3mm long. Body colour is usually a light yellow to tan colour and the abdomen is grey underneath. A common characteristic of the flies is distinctive red eyes.
Female fruit flies lay their eggs on the surface of rotting fruit, fermenting juices, soured milk etc. Fruit fly larvae feed on the yeast organisms and fungi growing in the fruit and vegetable materials. Through their feeding efforts, they soon turn their food into a semi-liquid mess and given their biology, they are a common pest in pubs and commercial kitchens.
Adult filter flies: 2mm, wings are almond shaped and the flies are very hairy. They are frequently mistaken for small moths since the wings are held roof-like over the body when at rest. They are weak fliers and often appear to be jumping or hopping.
Filter flies are often associated with moist, highly organic areas such as sink drains, sewage treatment facilities, storm drains, dung and rotten vegetation. Each female can produce about 100 eggs and, under optimum conditions, development can be completed in two weeks.
Should fruit or filter flies become abundant, a careful search for the larval breeding areas should be made, and the necessary housekeeping or maintenance measures taken. Any lingering adult flies may be controlled by the use of a residual insecticide or ULV treatment. Stagnant water may be treated with Bti (bacillus).