The plural of the noun 'fly' is 'flies'.
The verb 'fly' conjugates as follows:
I fly We fly
You fly You fly
He/She/It flies They fly
It is never, under any circumstances, spelled 'flys' or 'flyes'.
I want to put this in my status update so badly but I can't do it without hurting people's feelings. Instead, I'm putting it up here. Unbelievably, three different people have spelled either of the two incorrectly in their status updates over the past 72 hours. What iz the world coming 2?
Thanks for your patience with my orthography-bile!