Adult Queensland Fruit Fly are about 6 to 8 mm long and are reddish-brown coloured with yellow markings. Queensland Fruit Fly are most active in warm humid conditions and after rain. Queensland Fruit Fly might be seen walking on the undersides of leaves or on maturing fruit. They readily take flight if disturbed. The Queensland fruit fly (Bactrocera tryoni) is a species of tephritid fruit fly native to Australia. Their larvae hatch in various fruit species, causing significant damage to crops.