It is likely a beetle of some kind causing the problem, there are times when the wind whipping the foliage around can cause the thorns on the rosebushes to poke and tear the leaves. However in your case it sounds like a beetle issue. I would recommend spraying the rosebushes with a good insecticide, perhaps one that has systemic properties would be a good idea to deal with them.
Answered on August 7, 2016
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