Del Rio was the first place I lived as a newly wed. My husband who was an AF pilot. It was right after Hurricane Camille had devastated the MS Coast where I grew up. My dad thought Del Rio was the "end of the world" and told me, "Well at least there won't be any hurricanes there." And shortly after that, Del Rio had a hurricane go thru and do quite a bit of damage.
I don't remember mosquitoes there. I remember crossing the bridge into Acuna and feeling perfectly safe. (I don't think I'd do that now). And the local folks were so nice to us.