The Danish Mayfly, whose scientific name is Ephemera danica, was selected as the Insect of the Year for 2021.
Mayflies have existed for about 355 million years and today some 140 species live in Central Europe. Despite their fleeting time on earth in their final form, their developmental cycle is quite long.
Female mayflies lay thousands of eggs under water between May and September every year. Larvae hatch within a few days, and eventually develop gills. Buried in riverbeds, they take between one to three years to develop.
Shortly before the transition from aquatic to terrestrial life, a layer of air forms between the old and new skin of the larvae. By reducing its specific weight, the larva rises to the water surface.
Once there, the larval skin bursts and within a few seconds a flyable mayfly hatches. With no mouth parts nor an intestine, the fully developed mayfly has only a few days then to mate and lay new eggs before it dies.
entomologist：名詞，昆蟲學家。例句：Only entomologists can distinguish dangerous mosquitoes from harmless ones.（只有昆蟲學家能區分危險和無害蚊子。）
fleeting：形容詞，轉瞬的。例句：The witness only got a fleeting glimpse of the suspect.（目擊者僅瞬間瞥到嫌犯。）
larvae：名詞，幼蟲（larva）的複數形。例句：The tadpole is the larva of the frog.（蝌蚪是青蛙的幼蟲。）