Caterpillars

• Caterpillars, the larvae of butterflies and moths, sustain themselves by eating leaves. The distinctive holes created by caterpillars on rose leaves are irregular and taken out of the middle of the leaves. One way to eradicate caterpillars is to pick them off by hand and destroy them. Alternatively, apply an organic spray that consists of Bacillus thuringiensis, a bacterium that destroys the caterpillars but is considered safe for plants and animals.
  
  

Leafcutter Bees

• As the name suggests, leafcutter bees cut the leaves to use for building their nests. The damage of leafcutters is indicated by semicircles cut out of the edges of the leaves. Because these bugs aid in pollination, they shouldn't be destroyed. Pune away the damaged leaves instead.
  
  

Japanese Beetles

• If your rose leaves display a lace-like or skeletonized appearance, the Japanese beetle is the culprit. Adult Japanese beetles can be recognized by their metallic green bodies with copper-brown wing covers. They begin feeding on plants in June and feed on plants for four to six weeks before dying. Although the beetle's appetite is small, it's a group of these insects that wreak the most damage. Japanese beetles appear as white grubs in the larval stage and infest turf. This is the time to eradicate the pest. A long list of chemicals exist for treatment of grubs. These products remain in the ground for a long time and should be applied before the grubs appear in high risk sites. Ask at your local garden center for the best product to eliminate them.
  
  

Rose Slugs

• Rose slugs or inch worms are the larva of the rose sawfly. They eat the leaves and disappear into the soil to hibernate. Remove the slugs by hand and drop them into a bucket of water or oil, or blast them off the plants with water from the hose. Then spray the foliage with neem oil and apply beneficial nematodes or diatomaceous earth to the soil.