Q: My aunt has three roses, each 3 feet apart. The middle one, White Lightning, is getting eaten by something. I have used 2-in-1 systemic rose and flower care (granules) as well as 6-9-6 fertilizer on all three bushes plus other bushes around the garden. But the critter is eating the buds before they even get any color – but only the white rose. They don’t bother the other ones at all and they’re all different varieties. What’s up? Help!
Mary Pape, Rio Linda
According to UC master gardener Annie Kempees, the insect that is defacing petals of your white rose is called a hoplia beetle.
The adult hoplia beetles chew holes in flowers of various species, most notably the rose. The adult beetle (Hoplia callipyge) is primarily a problem in the Central Valley from Sacramento to Bakersfield.
They are about 1/4 inch long, reddish brown with silvery or coppery scales, causing them to appear iridescent in sunlight.
There is one generation of hoplia beetle per year, with their damage confined to about a 2- to 4-week period in spring, typically late March to May. That means the hoplia are about ready to strike.
The larvae typically overwinter in alfalfa fields or along fence lines or other areas with undisturbed vegetation. The larvae do no damage to the leaves or roots of roses; it is the adult beetles that do the damage. They prefer light-colored blossoms such as apricot, pink, yellow and most definitely white roses.
Hoplia beetles also may feed on the flowers of calla, citrus, irises, lilies, magnolia, olive, peonies, poppies and strawberries and on the young leaves and fruit of almonds, grapes and peaches, according to University of California experts.
These beetles can be removed by hand picking the adults from the plants or ground. Another method is to shake each rose cane over a small bucket filled with soapy water. The beetles will fall off into the bucket (and they can’t swim).
Rose growers have had some success with this method: Place 5-gallon buckets with water on either side of your white rose. Add a few drops of liquid detergent to each bucket to break the surface tension. The beetles are attracted to the buckets, where they’ll fall in and drown.
Infested flowers also can be clipped off and disposed of; don’t compost them.
Sprays are not very effective for the adults or larval stages and should not be necessary in a garden situation. Instead, keep on the lookout for these beetles and nip them before they nip the buds.
For more information on the hoplia beetle and its management, check out the hoplia pest notes available online from the University of California’s Integrated Pest Management website at www.ipm.ucdavis.edu.
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