It sounds like you have larvae of Japanese beetles or chafers in your soil. These have overwintered deep in the soil and rise to the surface at this time of year to mate and lay eggs. Primarily they attack lawns but after they have hatched, Japanese beetles in particular can cause plenty of damage to roses and other ornamentals. Remove and destroy whatever grubs you find. If you are diligent about this, you will probably not have to resort to poisonous pesticides. For a definitive diagnosis, take some samples to your local Cooperative Extension office (blue or yellow pages) and get advice from them.