Definition of black fly in English:

black fly

noun

  • 1A small black fly, the female of which sucks blood and can transmit a number of serious human and animal diseases. Large swarms sometimes cause distress to livestock and humans.

    • ‘In fact, in their effort to discourage the world's mosquitoes, blackflies, sand flies and ticks, consumers spend an estimated $200 million annually on sprays, liquids, lotions, candles and other anti-insect concoctions.’
    • ‘When you're not underwater, coat yourself in deet or be eaten alive by bloodthirsty blackflies.’
    • ‘Other blood feeding insects or mites that may occasionally be pests of poultry include: chigger mites, biting midges, and black flies (turkey gnats).’
    • ‘Similarly, as soon as I crossed the doorstep, the June hordes of bloodsucking blackflies and horseflies left off their hot pursuit.’
    • ‘Similarly, the device mimics a human by emitting a plume of carbon dioxide, heat and moisture, and an attractant, octenol, which targets mosquitoes, biting midges, black flies and sandflies.’
  • 2A black or dark green aphid that is a common pest of crops and gardens.

    sandfly
    and → buffalo gnat
    • ‘Most common are greenfly on roses and blackfly on nasturtiums and broad beans, but dozens of their relations also attack other plants.’
    • ‘One or two other insidious pests have crept almost unnoticed into my garden this month including blackfly, which have infested the tall flowering stems of the cardoons.’
    • ‘But the sunny weather has suited greenfly and blackfly, while mildew has affected several plants.’
    • ‘Hover flies and lace wings control aphids and blackfly.’
    • ‘And try to avoid ‘revenge spraying’ - which is what happens when blackfly, for example, have ruined your roses.’