Definition of mayfly in US English:



  • 1A short-lived, slender insect with delicate, transparent wings and two or three long filaments on the tail. It lives close to water, where the chiefly herbivorous aquatic larvae develop.

    Order Ephemeroptera: several families and many species

    • ‘Arctic species of mayflies, scale insects, midges, caddisflies and other groups are known to be parthenogenetic.’
    • ‘He could have added that they also consumed mayfly larvae, caterpillars, beetles, and ants.’
    • ‘If so many people of our own time are among the greatest Britons who ever lived, are we developing the long-term memory of a mayfly?’
    • ‘Although a lot of flying insects are referred to as ‘flies’ - butterflies, dragonflies, mayflies, and so on - the true flies belong to the Diptera.’
    • ‘In rivers rainbow trout will feed primarily upon the larvae of mayflies and caddis flies.’
    • ‘Rations include a variety of insect larvae, especially mayflies, blackflies, caddis flies, and midges.’
    • ‘Every day the sun sets behind blurred clouds of stonefly, caddis, midge or mayfly dancing against the horizon.’
    • ‘After the war he became physician to the Commonwealth embassies in Moscow and turned many a stone in search of mayfly larvae, to the bafflement of his footsore minders.’
    • ‘During the breeding season, they also eat insects, especially dragonflies, mayflies, and caddis flies as they emerge from their aquatic larval stage.’
    • ‘Excellent fishing was reported from this water for most of the week with good hatches of mayflies in most areas when the weather was suitable.’
    • ‘The most important insects vary with the season but the bulk of them are either mayflies, caddis, midges or terrestrials.’
    • ‘The first land snails appeared, and insects with wings that can't fold back such as dragonflies and mayflies flourished and radiated.’
    • ‘The students are looking at features to encourage biodiversity and create new habitats for sensitive species such as dragonflies and mayflies.’
    • ‘Young lads would then get a few farthings for catching dungflies and mayflies.’
    • ‘As larvae, the mayflies have spent two years feeding and growing underwater but now it is time for them to begin their brief lives in the air.’
    • ‘Such differences strongly suggest convergent reduction in the antennal flagella of odonates and mayflies.’
    • ‘When the mayflies emerge from the water as winged adults, they're called ‘duns.’’
    • ‘Although their roles as parasitic castrators has been documented, relatively little is known about the biology of ciliate parasites in mayflies.’
    • ‘Also unlike modern mayflies, the larvae apparently did not require flowing water.’
    • ‘Later in the year, when there are big hatches of adult mayflies and caddis flies, chub will position themselves on the edge of the current, ready to intercept the constant supply of food passing them.’
    1. 1.1 An artificial fishing fly that imitates a mayfly.
      • ‘I selected a small gold bead mayfly nymph tied on a size 12 hook, as it was white and clearly visible in the murky water.’
      • ‘Dapping natural and artificial mayflies also worked well.’
      • ‘Mayfly hatches appeared to be sparse but trout were still taking artificial mayflies.’
      • ‘I could clearly see my size 10 mayfly nymph as it proceeded downstream, bumping and lifting off the bottom.’