We've got black widows, rattlesnakes, probably brown recluse.
The flies, though, will kill you by annoying you to the point of absolute anguish.
So they must go. Mark Twain wrote a hilarious piece on Noah's Ark, about how they got all the pairs of creatures boarded, set sail, then had to go back because they realized that they forgot the flies...lol
If we had mosquitos here, they'd be goners as well.