There are a number of insects that can wreak havoc in your rose garden if you donít pay attention. Prevention is not really practicable but insect control is not only possible, it is almost mandatory if you and not the insect world are going to enjoy your beautiful roses. Donít let Mother Nature creep up on you and your roses.
The most common insect pests that can affect your roses are aphids, Japanese beetles, leaf cutter bees, spider mites and thrips. Aphids are the insects most usually found on and around roses. They can be red, green, yellow or black. They like the tender shoots of young plants but there are lots of natural predators who like tasty young aphids as well. If they become a problem you can try knocking them off leaves by spraying water on them but you can also use insecticidal soaps to control or eliminate them.
Japanese Beetles can cause a lot to damage to rose plants because they tend to invade in numbers and when they do, they are usually very hungry. These hard-shelled green, black and gold insects are particularly irritating since they can fly and often return to the scene of their crime for another snack after they have been repelled. Many gardeners find that the chemical Sevin is a good control measure but it only works when the pesky bugs are there so that it means you have to have constant vigilance and reapplication if you are going to prevent damage to your roses. If you have the time and patience you can always try picking them off by hand.
Leaf cutter bees cut perfectly round holes near the edge of the leaves and then they use these leaf pieces to create egg partitions inside of their burrows. The good news about leaf cutter bees is that their damage is purely cosmetic and kind of cute at that.
Spider mites can be red, black or brown and these tiny creatures suck the sap from the undersides of the rose leaves which causes the leaves to turn gray or brown. Mites come in bunches but you can usually get rid of them by washing the underside of leaves a couple of times a week. You can also use insecticidal soap or miticides to help deal with this problem.
Thrips are tiny brown insects that like to live inside of rose blooms. You can tell when thrips have been at work by a deformation of the flower and flecked or scratched petals. That means they have been eating at the inside of your rose blooms. They have a rasping mouth that scratches the petal surface when they feed and that creates the damage to the blooms. Thrips seem to prefer light colored roses like yellow roses and they tend to be at their worst during the warm summer months. Controlling thrips is a real challenge but some people have had success with insecticidal soaps and chemicals like orthene and malathion.
Other insects that may cause you problem in your rose garden include the rose leafhopper, the fuller rose beetle, the rose curculio, the rose slug, and flathead borers. Check with your garden center or nursery for the common symptoms and how to control these insects.