a pic would be most helpful, but i have had problems with rose chafers in the past and this sounds somewhat like them. Run a search for 'rose chafer infestation', as i have posted pics and see if this is what you have. If so Carabaryl has worked well for me. The invasion lasts about a week and a half before petering out (in my area at least).

It sounds like a beetle of some sort; apply beetle treatment. I had some small beetles about that size on my young apples. My treatment was I would go out at night when they were most active and smoosh by hand. I occasionally see them now that the trees are older but they don't cause appreciable damage anymore.

Scott