Leffcutter Bees-circular cuts on my leaves

I have found two dead bees in my room in the past week.  When I sit at my scrapbooking/sewing table I can see bees flying up in to the beams over my bedroom window.  There is a crack on the outside portion they seem to like.  At first I thought maybe we had a hive forming.  That can happen from time to time, however, upon further inspection we could not see anything. 

In the meantime I have been finding leaves with circles cut out of the edges on my best rose plant and my cherry tree. 
See these leaves?  That is what my plants look like.  It turns out the culprit is this little bee.  

Here, I have been looking under leaves, all around the plant trying to find out what is eating my plants, and it was a BEE.  This website will tell you all about Leafcutter Bees.  

To diagnose my problem I looked in the book, What's Wrong With My Plant (And How Do I Fix It?).  It clearly told me it was a leafcutter, but I didn't find the rest of the explanation to be satisfactory, so I went online!

Now that I know, I agree with my husband that we should seal up that beam.  Then next season I won't have to deal with as many, and there must be quite a few of them, because they are eating a lot of leaves.  Also, I think it is rather cool that a bee can cut such perfect little circles out of leaves, but I really don't want them to hurt my new little cherry tree.  Next year I have plans for at least two more trees, so I don't want a big number of them!  Isn't nature awesome (really, I do believe it is)!