Many insects eat holes in the leaves of rose bushes. The damage can range from ragged leaves to complete defoliation. The damage, while not pretty, is generally not enough to cause the rose bush to die. Remove the affected leaves by pruning the rose bush. Watch for pests as you work. Rose growers who do not grow organically may find that using a rose fertilizer with systemic insecticide solves rose pest problems.
Hollow rose bush stems attract leaf-cutter bees, according to Texas A & M University. The leaf-cutter bees use the plant material removed from the rose leaves to create walls in the nesting cells where the young bees develop. These bees are important pollinators, according to Clemson University. It is best to simply remove the affected leaves if the holes bother you.
Large holes in the leaves of rose bushes will not appear until the rose slug larvae mature, according to the University of California. Young larvae, however, will skeletonize the lower surface of the leaf. Although the larvae may look like a caterpillar, they are not. Remove them immediately by handpicking. Spraying the rose bush with a hard stream of water from a hose can dislodge them from the underside of the leaf. The best time to look for them, according to Clemson University, is at night. Soil drenches, insecticidal soap and horticultural oil are additional options for control of rose slugs.
Japanese beetles are one of the worst of the rose pests because they eat both the leaves and the roses. Although it is more common to see leaves skeletonized once the beetles are on them, there are instances where the leaves simply have holes in them. Numerous control options are used for these pests, according to Clemson University. Milky spore will destroy grubs in your lawn but will not do anything for controlling beetles that fly in from other yards. Japanese beetle traps, according to Clemson University, simply attract beetles, so unless you can position it 50 feet from the plants you wish to protect, it is useless. The most effective method is to handpick the beetles during the early evening hours. Brush the beetles into a jar filled with hot soapy water, and put a lid on it. Shake the jar to submerge the beetles. Other natural control methods include poultry, which love to eat these pests, and using netting to keep the beetles off your flowers. Several chemical insecticides, according to Clemson University, work as well.