Nuisance provisions of the Public Health etc (Scotland) Act 2008: guidance

SECTION 3 - FRUIT FLIES (DROSOPHILA)

Classification

Fruit flies compromise several species of the genus Drosophila (family Drosophilidae).

Habitat

Attracted to ripened or fermenting fruit and vegetables. Associated with commercial composting activities and fruit & vegetable producers, wholesalers, and packers. Fruit flies can be a problem year-round in domestic kitchens.

Health Impact

Fruit flies do not carry disease but they can contaminate foodstuffs particularly where there are poor hygiene standards or exposed, ripe fruit.

Nuisance

The sheer numbers that congregate can create a nuisance. As a guideline, an occupier will normally experience some distress if there are 50 or more 'flying' fruit flies present in any one room at any one time on three successive days.

Assessment

Find the source of attraction and breeding sites. Inaccessible breeding sites (e.g., waste-disposals and drains) can be evaluated by taping a clear plastic food storage bag over the opening overnight. If flies are breeding in these areas, the adults will emerge and be caught in the bag.

Controls

The best control measure is elimination of the sources of attraction. Produce that has ripened should be covered rather than discarded in the open as a rotting potato or a waste or recycling bin which is not emptied or cleaned can breed thousands of fruit flies. Where regular spillages of fruit juice or pulp inside buildings attract fruit flies, windows and doors should be equipped with tight-fitting (16 mesh) screens to help prevent adult fruit flies from entering from outdoors. All spillages and accumulations of fruit and vegetable juice and pulp should still be cleaned up regularly and thoroughly.

Once a structure is infested with fruit flies, all potential breeding areas must be located and eliminated as the problem will continue no matter how often insecticides are applied to control the adults. Once the source has been eliminated and flies given time to disperse an aerosol insecticide can be used to kill remaining flies.