Beetles are attracted to roses and a wide array of other trees and shrubs. They feast on the tender cane growth and leaves, and then overwinter and breed in the soil below. Effective home remedies for beetles focus on physical removal and preventing access to the plants. There are folk treatments that involve macerating dead beetles in liquid and then spraying plants or using purportedly beetle repellent companion plants. According to Steve Mayer at Purdue University Extension, these treatments are ineffective and not worth the effort involved.
Manual Removal & Drowning
Roust the beetles from the rose plants during the morning hours when they are slow to respond or move. Knock or flick them them into a bucket or jar filled with soapy water using your hand, a stick or an old paintbrush. They will drown and can be thrown away. While this seems unpleasant, relocation is not really a viable option, as the beetles can fly right back. Remove beetles immediately when you see them to prevent other beetles from being drawn to their brethren and congregating.
Sun and moisture-permeable cheese cloth, mosquito netting or fine mesh window-screen fabric with holes no larger than 1/4 inch can be laid over your smaller rose bushes. Tie it snugly around the lower trunk to physically prevent beetles from accessing your roses. Remove in the late summer or fall or when beetle populations have moved on.
Washing the Plants Down
A stiff spray from a garden hose can dislodge and temporarily relocate beetle populations, as they do not like to be wet. Roses do not like to be consistently wet either, so do this only occasionally and in the morning hours when the sun is shining and can dry off the foliage after the shower.