Fruit Fly / Vinegar Fly / Fermentation Fly

Scientific Name: Family Drosophilidae

How to identify a fermentation fly

Fermentation flies (Dacus spp.) are important pests to commercial industries and can cause much economic damage if unchecked. Vinegar (Fermentation, Bar or Beer) flies may become a nuisance in homes, restaurants, fruit markets, etc., especially when associated with decaying or rotting fruit and vegetables. Adult vinegar flies are about 3-5mm long, dull brownish-yellow to brownish-black with red eyes in some species. The head and thorax are tan-coloured, while the abdomen is black and grey underneath.

These should not be confused with the Queensland Fruit Fly Bactrocera tryoni that is a significant pest in the Agricultural / Horticulture in Australia.

Where are fermentation flies commonly found?

Fermentation flies are found primarily around decaying fruit. Indoors, these flies may be seen hovering around overripe fruit and vegetables, baked goods containing yeast, garbage cans and beverages/empty beverage containers, such as fruit juices, cider, soft drinks, beer, wine and vinegar.

Why are fermentation flies considered a pest?

Although fermentation flies have a potential to spread disease they are considered more of a nuisance pest than anything else. Populations can build up quickly and be very annoying for customers while eating or drinking. Contamination or food and drinks is also possible.

What is the biology and lifecycle of a fermentation fly?

Fermentation Flies have a lifespan of between 12 and 33 days. Females lay approx. 100 eggs in 24 hours. Under ideal conditions it takes 10 days for Fermentation Fly to progress from an egg to an adult. Adult flies are sexually active within 12 hours of emerging.

Management Tips for Fruit Fly/Vinegar Fly/Fermentation Fly

Fermentation Flies can prove extremely difficult to control and often the underlying issue is hygiene. The problem will continue unless the Hygiene issues are fixed. To simply apply a chemical without addressing the underlying reasons for the fly infestation will fix not the problem.

Tackling fermentation flies needs a multi faceted approach:

• Breeding Site Removal –

  • Fermentation flies will breed on any decaying organic material. This can include floor / waste drains, garbage bins, food scraps under counters etc, coffee grinds.

  • Cleaning drains using products that contain enzymes will remove mould and organic matter from drains so eliminate breeding sites for fermentation flies.

  • Garbage bins should be emptied regularly and should always have lids on them. Garbage room doors should be kept closed at all times.

  • Regular cleaning of floors, surfaces and hard to get areas where food scrap accumulate should be carried out to illuminate breeding sites.

  • Make sure drink trays do not contain liquid for a long period of time and are cleaned regularly.

  • Inspect the premises for other possible breeding sites such as over watered pot plants, leaking plumbing pipes.

• Traps

  • a number of disposable traps are available that attract adult flies and this will reduce the adult population. Normally these traps contain apple cider vinegar or similar to attract the flies.

  • Glueboard Flying insect units can help catch adult flies especially if they are placed close to problem areas eg under counters.

• Chemical control

  • Chemical control should only be done in conjunction with other methods of control

  • Treating surfaces where the Fermentation flies land with a residual chemical will kill adults that land.

  • Metered Aerosol Dispensers - these can be effective against flying insects in limited spaces e.g. store room, cleaner’s room and garbage room. They have limited effect in large open areas.

  • Space spaying will kill adults and reduce the problem in the short term. Space spraying will not provide long term control.