Diptera : Drosophilidae : Drosophila melanogaster
Vinegar Fly (Drosophila melanogaster), is a small fly of the family Drosophilidae that is attracted to rotting and overripe fruit, and other decomposing vegetable matter. They are common in compost bins, in orchards and vineyards, and might also be attracted to fruit bowls indoors. Vinegar Fly is nearly always a nuisance rather than a serious pest.
Vinegar Fly may also be known as an ‘Indoor Fruit Fly’ or a ‘Ferment Fly’. However, in Australia the term ‘fruit fly’ is reserved for serious fruit pests of the fly family Tephritidae (e.g., Queensland Fruit Fly and Mediterranean Fruit Fly).
The take home message with Vinegar Fly is that it is rarely, if ever, a serious pest. Vinegar Fly is most likely to only be a nuisance in a home garden. Adult Vinegar Flies are attracted to volatile compounds given off by the yeasts associated with decomposing fruit and other decomposing vegetable matter.
Vinegar Flies may occasionally breed in fruit that is still hanging on a tree, but that fruit has to be split or damaged in some way. Vinegar Flies are notorious for breeding in compost bins, which makes sense given that the flies are attracted to decomposing vegetable matter.
Some people find Vinegar Flies annoying, others don’t. If you are in the former camp, prevention is your best strategy. Fallen fruit or damaged fruit from fruit trees, or fruiting vegetables like Tomatoes, should be picked up and buried, or composted, or disposed of. Seal your compost bins so that female Vinegar Flies can’t get inside to lay their eggs.
Vinegar Flies sometimes hang around fruit bowls indoors, and anecdotally seem particularly attracted to bananas. To help control Vinegar Flies in your home, use Yates Home Pest Indoor Fruit Fly Trap. It contains a liquid lure that attracts Vinegar Flies – they fly into the trap, become stuck and eventually drown. For heavy infestations, you may need to use more than one trap at a time. It’s also a good idea to cover your fruit with a net to prevent the flies walking all over it.
The Vinegar Fly (Drosophila melanogaster) is a small fly, which originated in sub-Saharan Africa and is now found on every continent and most islands around the world. People overseas refer to these flies as ‘fruit flies’, a name which means something quite different here in Australia. The pest flies that damage fruit in Australia, such as Queensland Fruit Fly and Mediterranean Fruit Fly, are members of the family Tephritidae. Vinegar Fly is a member of the family Drosophilidae.
Another common name for this fly is ‘ferment fly’, which is a much better name than ‘fruit fly’ as the flies are attracted to volatile compounds produced by yeasts in fermenting fruit. They can be a nuisance under fruit trees where overripe fruit has been allowed to remain on the ground. They may even breed in fruit still on the tree that has been damaged in some way. They can also be a problem around wineries where fermentation is de rigueur. Vinegar Flies also breed in the decomposing vegetable matter in compost bins.
The Vinegar Fly is usually only a nuisance, but it has a relative that occurs in other parts of the world that we definitely don’t want here. Drosophila suzukii, known as ‘Spotted Wing Drosophila’, is a serious biosecurity threat due to the potential damage it could cause in various soft-skinned fruit crops if it arrived here. Drosophila suzukii lays eggs into healthy fruit, unlike Vinegar Fly which does not.
The adult Vinegar Fly is about 3 mm long, yellow-brown in colour, with a rounded head bearing large red eyes. There are black stripes on the upper surface of the abdomen and males have a dark tip to their abdomen.
Eggs are about 0.5 mm long, silvery and ovoid shaped.
Larvae are white maggots, which grow to about 3 mm long.
Pupation occurs in a yellowish-brown seed-like puparium that is about 2-3 mm long.
Vinegar Flies develop through a lifecycle of complete metamorphosis – egg, larva, pupa, to adult fly. Female flies lay about 50 eggs at a time and they can lay on average about 500 eggs in their lifetime of a few weeks. The eggs hatch a day later, and the larvae feed for about a week, before pupation takes place – either within the fruit or in dry soil. Adult flies emerge a few days later and are ready to mate within a day. The full life cycle may be as short as 8 to 10 days depending on the temperature.
Image above: Vinegar Flies attracted to fresh compost
(image courtesy of Elise Dando)
Adult Vinegar Flies and their larvae feed on the yeasts growing on overripe fruit, including those of fruiting vegetables like Tomatoes, which provides the nutrients required for adult survival, reproduction and larval growth. Vinegar Flies may occasionally breed in fruits still on plants that have been damaged or split.
Vinegar Flies readily breed in compost bins. They contribute to the decomposition cycle but some people find them annoying.