Mayfly vs. Fishfly

Mayflynoun

Any of the many fragile insects of the order Ephemeroptera that develop in fresh water and live very briefly as winged adults.

Fishflynoun

(Canada) A mayfly.

Mayflynoun

slender insect with delicate membranous wings having an aquatic larval stage and terrestrial adult stage usually lasting less than two days

Fishflynoun

Any insect in the corydalid subfamily Chauliodinae. Unlike most dobsonflies (subfamily Corydalinae) they don't have the enlarged mandibles typical (at least in the males) of that subfamily.

Mayfly

Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern U.S.; also up-winged flies in the United Kingdom) are aquatic insects belonging to the order Ephemeroptera. This order is part of an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies.

Fishflynoun

a fly similar to but smaller than the dobsonfly.