without using harsh chemicals, you can always try a water, mineral/vege oil, soap mixture which you can google. Otherwise, you will have to go with a chemical like malathion or some other insecticice. they are more effective, but I'm not a big fan of using those strong chemicals around my house.
do you mean it bores into the flower bud? Google information on curled rose sawfly.
I was told to use dawn dish soap and water then spray it on. One problem, I forgot the ratio of water to dish soap. Sorry!