Dayfly and Ephemerid

Dayfly noun - Slender insect with delicate membranous wings having an aquatic larval stage and terrestrial adult stage usually lasting less than two days.

Ephemerid and dayfly are semantically related. In some cases you can use "Ephemerid" instead a noun "Dayfly".

Ephemerid noun - Short-lived insect.

Dayfly and ephemerid are semantically related. Sometimes you can replace term "Dayfly" with "Ephemerid", this nouns are similar.