The bees that cause precise circles or ovals in foliage are small and hairy, either black, green, purple or blue. They seem to prefer foliage of roses, although any tree or shrub that has a shiny, firm leaf may be cut. Bees are docile and rarely sting humans and can be beneficial due to pollination. Eliminate potential nesting sites around rose bushes by clearing away weeds and leaf debris or cover plants with floating row covers. There is no cure.