Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Fruit fly bait sprays & traps (507)

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  • Monitoring fruit flies: (i) commercial growers – traps for male flies with wicks containing pheromone and insecticide (spinosad, spinetoram, fipronil). Place traps on lower branches of crop or in trees nearby for low-growing vegetable; (ii) smallholders – pheromone not always accessible, therefore assume fruit flies always present.
  • Commercial sprays: See examples given in Full Fact Sheet and follow manufacturers’ instructions. Note the following:
    • Contains protein (often yeast waste from brewer), plus insecticide (sometimes with sugar and thickening agent, e.g., guar gum or xanthium gum).
    • Insecticides: spinosad; spinetoram; fipronil; malathion or abamectin.
    • Start spraying after fruit set, continuing until 3 days before harvest (malathion), 7 days (abamectin); spinosad has zero withholding period – use as directed.
    • Spray 'spots' as a stream, with nozzle fully open, NOT as a fine spray)
  • Smallholder home-made traps:
    • Use plastic soft drink or water bottles (600mL is best; 1.25L can be used, but require more bait)
    • Make 3-4 holes, size of small finger on shoulder or above halfway up the bottle
    • Fill to about ¼ full with mixture made of:
      • 1L water.
      • 50mL cloudy ammonia.
      • 1tbsp sugar.
      • 5mL vanilla essence (artificial).
      • 1tbsp yeast extract (e.g., Vegemite®, or Marmite®).
      • A few drops non-scented dish-washing liquid.
    • Clean containers and replace weekly.
    • Hang 2-3 in shady parts of large tree, 1.5-2m above ground, 3-4m apart.
    • Alternatively, make up (i) 1tsp of Vegemite® or Marmite®; 1tsp sugar; 2-3 drops non-scented dish-washing liquid; OR (ii) blend host fruit in 1L water (liquid enough to drown adult flies) and place in plastic bottles with holes (see above).

AUTHORS Graham Walker & Grahame Jackson
Information from Making a fruit fly trap. Department of Primary Industries and Regional Development. Western Australia. (; and Messing R (1999) Managing fruit flies in farms in Hawaii. Cooperative Extension Service, College of Tropical Agriculture & Human Resources, University of Hawaii at Mania. Hawaii. (

Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/185: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Secretariat of the Pacific Community.

Measurements: tsp = teaspoon; tbsp = tablespoon; mL = millilitre; L = litre; m = metre; g = gram.

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