mayfly
Refers to the insect order Ephemeroptera. In everyday use, the kana form かげろう is standard.
On a summer evening, many mayflies were flying above the river.
ephemerality; transience of life
Metaphorical use, often in literary or poetic contexts, likening life to the short-lived mayfly. Common in phrases like かげろうの命.
He spoke feelingly that human life is like that of a mayfly.
Only when written 蜻蛉
Archaic word for dragonfly. In modern Japanese, トンボ is used instead. The kanji 蜻蛉 is now read as とんぼ or せいれい.
See also: トンボ
In old waka poetry, 蜻蛉 is sometimes read as かげろう.
The modern standard word for dragonfly. かげろう in the archaic dragonfly sense is replaced by トンボ.
Cicada, another insect often used as a metaphor for the transience of life, though with a different seasonal association.
Archaic kanji form for dragonfly, now normally written トンボ. The reading is a gikun.
Katakana spelling is sometimes used, especially in biological or field-guide contexts.
Rare kanji form for mayfly and the associated ephemerality metaphor. The reading is a gikun (meaning-based reading).
The word is native Japanese. The kanji 蜉蝣 and 蜻蛉 are Chinese borrowings applied as gikun (meaning-based readings) to the existing Japanese word かげろう. The exact origin of かげろう is uncertain.