My wife is tossing around the idea of camping on or near Chesapeake Bay for
Columbus Day weekend....she's looked at the KOA at Smiths Island in VA.

Yes, unless there has already been a hard freeze, forget it! Years ago I tried to revive the old "Buses Near the Bay" event, camping at Point Lookout, Maryland. The mosquitoes were horrible!! We couldn't stand to be outside for more than a couple of minutes. And the park service told me they stop spraying after Labor Day, even though the park is still open. And with all the rain we've had this year, they're probably pretty bad.   Jeff