Fruit & Filter Flies

There are many different species in this family but their biology and characteristics are similar.  These are relatively harmless to man and do not bite although they can become a source of annoyance, particularly in pubs. Despite their relative harmlessness a cloud of fruit flies buzzing around your bar is not the best impression for customers, who may mistake their presence for a sign of low standards of hygiene in your pub. So keeping them at bay is essential.


Fruit fly adults are small (approx 3mm) yellow/brown flies with a dark striped abdomen.  The prominent compound eyes are generally red in colour although can be dark in some species.

Filter flies such as the Owl midge are 3-4mm in length, light grey / brown in colour and have the appearance of a small moth.


Fruit flies are commonly associated with bars where they breed on fermenting liquids in drains, insulation around leaking drink pipes and other damp areas.

Filter flies breed in wet organic matter found in drains.

Both species are usually associated with poor standards of hygiene, but some species can be equally at home in over-watered plant pots or a piece of decaying fruit under a kitchen bench, blocked roof guttering etc.

Life Cycle

Fruit flies: Eggs are white and 1mm long.  Females lay between 400 and 900 eggs in batches of 15 to 25.  The emerging larvae feed on damp, decaying and fermenting organic material, taking about 5-6 days to develop.  Pupation occurs out of the feeding material and lasts 2-5 days.  In warm conditions, development from egg to adult can take as little as 2 weeks.

Filter flies: Eggs are laid in a suitable medium eg, drains.  Larvae hatch from eggs, normally within 48 hours, and feed in the rotten organic matter for about 14-15 days.  Pupation is a matter of a few days before the adults emerge.  Adults live for 2-5 days.

Control Methods

Good housekeeping is the best form of control.  Thorough cleansing of drains, cleaning up of drink spillages, repair of leaking drink supply pipes, sealing of cracks in flooring where residues are likely to occur.  Application of residual insecticides to alighting surfaces will help control adult flies as will application of ULV insecticides.  These services are available through a professional pest control company.