Back on topic - right at the beginning someone said "squirty multi-surface cleaner". Perhaps that was too subtle, so I will name the magic bug solvent I use as "Pledge".
Intended for polishing furniture, the waxy liquid acts as a mild solvent for removing dead bugs from the leading edges if you have let them dry to a crust. Spray a LOT on - we are not polishing furniture here, we're softening corpses - wait a few moments, and then wipe 'em off. It definitely works better than water.
And no, I don't recommend it for the windows.