I was recently trying to think of another way to say "on the fly", in the context of a performance, speech, or action. I thought of the idiom "winging it". I then wondered if the origins of these two idioms are in any way related, because of the words "wing" and "fly". Did one of these idioms spawn from the other?
One comes from baseball, the other from the theater.
On the fly (Baseball) still in the air; -- said of a batted ball caught before touching the ground.
Webster's Revised Unabridged Dictionary http://www.finedictionary.com/on%20the%20fly.html
To do something on the fly is 1856, apparently from baseball.
When the catcher sees several fielders running to catch a ball, he should name the one he thinks surest to take it, when the others should not strive to catch the ball on the fly, but only, in case of its being missed, take it on the bound. ["The American Boys Book of Sports and Games," New York, 1864]
wing it - informal speak or act without preparation; improvise : a little boning up puts you ahead of the job seekers who try to wing it. [ORIGIN: from theatrical slang, originally meaning [to play a role without properly knowing the text] (either by relying on a prompter in the wings or by studying the part in the wings between scenes).]
New Oxford American Dictionary
"On the fly" appears to be the older between the two and suggests a sense of hurry while "wing it" refers more to improvisation. Though the suggested meanings are somewhat related I can't find evidence of a common origin.
- In a hurry, on the run, as in I picked up some groceries on the fly. The transfer of this expression, which literally means "in midair or in flight," dates from the mid-1800s.
Improvise, as in The interviewer had not read the author's book; he was just winging it. This expression comes from the theater, where it alludes to an actor studying his part in the wings (the areas to either side of the stage) because he has been suddenly called on to replace another. First recorded in 1885, it eventually was extended to other kinds of improvisation based on unpreparedness.
Verbal phrase wing it (1885) is said to be from a theatrical slang sense of an actor learning his lines in the wings before going onstage, or else not learning them at all and being fed by a prompter in the wings; but perhaps it is simply an image of a baby bird taking flight from the nest for the first time (the phrase is attested in this sense from 1875). (Etymonline)