What causes this thinning?
I've attached 3 pictures and am trying to figure out why these bushes are thinning out. Any ideas? I'm thinking bugs. Perhaps Japanese Beetles; that's the only bug I found on the bushes. The brown, dead leaves, you see are from when I hedged them about two weeks ago.
My guess would be deer... do you have them in your area? Usually when I find severed branches like that it's deer and they do go for euonymous (burning bush). I convinced my parents to let me hack back one of their overgrown euonymous bushes last year with the promise that it would fill back in within a year. My dad wasn't too happy when every time fresh new branches started to grow they got nipped by deer all season. This year it's done well and filled back in (though I plan to take it out for them this fall anyway and replace it with something better for the space).