Insects with wings of short span (8)

I believe the answer is:

ephemera

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'of short span' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

(Other definitions for ephemera that I've seen before include "Mayfly - something short-lived" , "Flyer" , "Passing items" , "Something that lasts or is useful for only a short time" , "Things lasting only briefly" .)

I've seen this clue in The Globe and Mail.

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