How much will a hole in the wing of a bumblebee affect its flying? let's assume the holes are round shape in the middle of both wings. if the size is 1% of the whole wing, how much will be the impact? i assume this is not linear, how much will be affected if the hole becomes bigger?
i suppose this is quite difficult as bumblebee's wings are moving, and might follow a complex route. are there research on this area?

 A: While a full fluid dynamic and biomechanical treatment is complex, I think one can make a simple scaling argument: 
Bumblebees are small. That means that the Reynolds number of fluid flow around them also gets scaled down; in fact, to a bumblebee air is a pretty viscous fluid. Hence the resistance to flowing through a small hole will be pretty big. 
One can roughly estimate this by thinking of the hole as an orfice plate (in a very large pipe, so $\beta\approx 0$). Since the mass flow is proportional to the surface area of the hole we should guesstimate that a 1% hole has a pretty minor effect both on escaping air and the overall flow pattern.
In fact, looking at small moths one often finds that they have wings that are little more than a few feathers with pretty noticeable holes. This is just like how one can use a pole not just to push a punt in a river but also use it as both an oar and a rudder: in the viscous water environment the rod has enough area to matter anyway. 
A: You are right. This is a spectacularly difficult problem. Considering the many assumptions that need to be made re: wing shape, wing motion, bee weight size & shape, flight profiles, and location of hole, a theoretical model will likely be woefully divergent from reality.
I suggest an empirical study. This will be necessary regardless just to verify the assumptions made, so you may as well go one step further and hole punch them too.
