Insect Enemies of Roses
Time and space limitations will ensure that omission of some insects will protect the guilty but the following roster will list the most damaging insects which may be found in the average rose garden. Your university extension office can give information on these and any other insects unfamiliar to you. If no personal help is available, a reference specific to roses such as Ortho’s All About Roses gives accurate and helpful information about all facets of rose gardening.
APHIDS are probably number one on a rose’s hate list. Large numbers of the 1/16-inch- long, soft-bodied, green, white, brown or red insects can be found sucking sap from rose stems. A strong jet of water or a broad spectrum insecticide will control them.
BEETLES such as Fuller beetles, rose chafers and rose curculio will feast on flowers, stems and leaves. Hand pick the adults or spray with a broad spectrum insecticide. Drench the surrounding soil with insecticide to kill the larvae. Cucumber beetles, too, hide in buds and flowers and bore holes in them. Spray into the blooms generously.
CANE (PITH) BORERS are the larvae of rose stem sawflies, rose stem girdlers or small carpenter bees. Eggs are deposited in the rose through wounds or pruned tips of canes. Prune the affected cane until a center hole is no longer visible. Dispose of cut material in the trash and seal the cut end with nail polish or white glue.
CATERPILLARS Green or yellow wormlike larvae of various insects can do serious damage to plants by eating holes in leaves or defoliating the plant completely. Apply a broad-spectrum insecticide.
SPIDER MITES establish huge colonies underneath leaves. Untreated, they may defoliate the plant by sucking its sap. Only miticides applied every 28 days to match their reproduction cycle will have any significant effect on them. Sprays must be directed to the underside of the leaves where the mite colonies which resemble salt-and-pepper particles are located.
THRIPS are dark, have four fringed wings and are only 1/16 inch long. They feed on tender young leaf tissue, flower stalks and buds. Direct insecticide sprays at tender growth and drench the soil surrounding the plant to kill the larvae.