Queensland fruit fly

Bactrocera tryoni

The adult is wasp-like, red-brown with yellow marks, and about 8 mm long. Unlike cucumber fruit fly there is no central yellow mark down the length of the dorsal surface of the thorax between the wings. Fruit flies hold their wings outstretched in a horizontal position when walking. They flick them in a characteristic manner.

Damage: Major and frequent pest. Activity is greatest in warm humid conditions and is particularly important where tree-ripened fruit are concerned. Adults lay eggs ('sting') in the fruit and the larvae feed in the flesh. Affected fruit are readily recognised since rots develop rapidly and the skin around the sting marks becomes discoloured. Queensland fruit fly damage is more severe during mid and late summer than at other times. Large numbers of flies can be expected after good falls of summer rain; fruit flies become active after periods of rain or high humidity. To monitor fruit fly activity hang male lure traps under the shady canopy, where flies tend to rest. Check the number of flies trapped each week. The recommended trap contains a synthetic attractant combined with a fumigant insecticide. Growers need to seriously consider whether fruit flies are causing sufficient damage to warrant spraying. A number of traps (one per hectare) should be hung in the middle of each large orchard block of 5.0 ha or more according to manufacturer's instructions. Inspect traps at weekly intervals from the end of flowering and until the completion of harvesting. Control maybe necessary as soon as two flies per trap per day are caught.