Beetle Pests on Roses

Japanese Beetle

• Japanese beetles have long bodies that are mostly green with copper-brown wings. They have spots of white hair that extend from underneath their wings on either side of their bodies. They usually start feeding on roses in June, beginning at the top of the bush and working down its stem. They continue to feed on rose petals and foliage for about a four- to six-week period until the beetle eventually dies. Japanese beetles have short life spans of between 30 and 45 days. Although a single beetle usually does little harm to roses, a large population of Japanese beetles can do significant damage.

Manual Control

• Since beetles attract more beetles to feed on the same plant, it's wise to remove beetles once you discover even one. Physically remove beetles with your hands or gently shake the bush to knock off insects when one or only a few are spotted. If you submerge beetles in soapy water, they will die. Place a protective covering, such as a cheesecloth or fine netting, over rosebushes in June and July to protect them from beetle infestation.

Chemical Control

• Spray your rosebushes with an insecticide formulated to eliminate beetles. Insecticides such as cyfluthrin, bifenthrin and deltamethrin contain pyrethroid -- a chemical effective at managing beetles. Certain botanical applications, such as pyrethrins in canola oil, are also successful beetle deterrents. No matter the type of product you use, cover the entire rosebush, including its blossoms and foliage, with the insecticide before and during its feeding cycle. Chemical formulas with pyrethroid generally last one to two weeks and botanical applications last only three or four days before you need to reapply them.

Considerations

• Although some home gardeners use beetle traps obtained from a garden center, the traps alone generally don't get rid of all beetles. Even though traps, which illicit a sweet-smelling scent designed to lure beetles, do, for the most part, attract beetles, traps don't always catch each and every beetle that it draws near. For this reason, beetles usually persist. Another downside to using traps is that while they might keep beetles away from certain plants, depending on where they're placed, they might divert them to another area of your garden or landscape. It's generally best to use a combination of manual and chemical control practices to discourage beetle infestation.