It can stagnate to the point of bugs not having much of an issue staying on the wing during flight. I remember a case when I was flight training where we had a

It can stagnate to the point of bugs not having much of an issue staying on the wing during flight. I remember a case when I was flight training where we had a little spider as a passenger on the top of the starboard wing for the duration of the flight. The little guy didn't fall off until the wing stalled out when we were landing.