Here are some of the most common insect pests of roses and how to recognize them.

Aphids .  Small, pear-shaped insects that congregate on new leaves and flower buds, sucking plant juices, leading to plant damage and distorted growth. Aphids come in many colors and secrete a sticky, sugary substance called honeydew. The honeydew often turns black as it becomes infected with sooty mold, which makes your roses look even worse. If that's not enough, honeydew also attracts ants, which feed on beneficial insects, which further complicates problems. Eliminate the aphids and you'll also get rid of the sooty mold. Most insecticide sprays, including insecticide soap, are effective.  Aerosol insecticides labeled for plant pests will also work – spray up-wind and allow the mist to drift through the plant.  Later, wash off the insects with hose water.  A chemical free method would be to introduce ladybugs to your garden to keep aphids under control.

Beetles .  A number of related beetles, including Japanese beetles, June beetles and rose chafers, are serious pests of roses. One or the other is common in most parts of the country.  Sprays, dust, and “shaking.”  Sprays of Carbaryl (Sevin), or Diazinon are somewhat effective. Apply Bp (Bacillus papillae) or ‘milky spore’ when the grubs are first detected in spring or late summer.  Neem oil, a new natural insecticide, or its derivative Azadirachtin, has show some limited control.  Practical, yet effective, is to spread cloth or plastic on the ground and shake the beetles off the plants.  Traps can also be effective if placed away from your roses.

Rose Midge .  If your roses seem otherwise healthy but the flowers just don't open properly, its probably caused by the rose midge. These nearly invisible insects scrap new growth particularly flower buds, causing them to shrivel and turn black. Spread Diazinon granules on the ground below the bush to control this pest.  Sprays are of limited value here because of midge life stages in the ground.

Scale .  If stems of your roses are gray and crusty and occasionally die out, it may be one of several species of scale.  Insecticidal potassium soap sprays work as well as oil sprays.

Spider Mites .  These tiny spider-like pests are just about invisible to the human eye, but you can definitely see the damage they do. Spider mites suck plant juices from rose leaves, causing them to turn yellowish with a silvery sheen, and often drop off. They usually congregate on the undersides of the leaves, and if the infestation is bad enough, you'll see the webbing there. Another way to test for mites is to hold a piece of white paper under a branch and shake it. If you see any tiny specks fall on the paper those are mites. Spider mites are most common in hot dry weather and on dusty plants. Insecticide soap, miticides, and high-pressure hose water.  All treatments must be applied from the bottom up in order to contact the insect, which is always on the leaf underside.

Thrips .  Another tiny pest that you'll have trouble seeing with the naked eye, thrips feed on rose petals, causing them to be deformed and discolored. Buds often fail to open properly.  Apply insecticides containing acephate when the buds are pea-sized, then again at two-week intervals.  Keep your eye out for these pests, they come back more than once. Follow instructions on the label for mixing and spray intervals.