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Attack of the hoplia beetles

Sacramento Digs Gardening
BY Debbie Arrington PUBLISHED MAY 4, 2020

What happened to this rose? Hoplia beetles attacked it. (Photos:

Debbie Arrington)

This pest loves to eat light-colored roses and other spring flowers

What’s eating your roses? If it’s early May in Sacramento, most likely you’ve been visited by hoplia beetles.

This pest loves light-colored roses, especially white, yellow, apricot or light pink. It chews round holes in the petals as it works its way to the tasty center. It likes the unopened buds, too. But it doesn’t eat rose leaves – just the flowers.

According to UC Cooperative Extension master gardeners, hoplia beetles also 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.

In other words, these beetles are hungry, destructive pests.

Members of the monkey beetle family, hoplias are common in our area from late March through May, depending on the weather. More than 300 species of hoplia are known. Our most common local hoplias are Hoplia callipyge . The adults are brown, oval and about 1/4 inch long.

The adult beetles can fly, which is how they made it to your roses. They over-winter in the larval or pupal stage underground in undisturbed areas, feeding on roots and decaying vegetation. They emerge from the soil as adult beetles with an appetite. After feeding for several weeks, they fly back to their nesting site to lay eggs.

This life cycle takes a full year, which is key to their control. They’re only a problem right now. By the end of May, they’ll have disappeared.

This hoplia was eating a rose Sunday in midtown Sacramento.

Because the beetle tunnels into the bloom, chemical pesticides are not effective – or necessary. The pesticide has to come in direct contact with the beetle to kill it. In addition, systemic insecticides aren’t effective because concentrations of the poison in the plant’s petals aren’t high enough to be effective.

When you see a rose or other flower with hoplias, cut off the whole bloom, drop it in a plastic bag, seal and dispose of it.

Or use the bucket method: Fill a 5-gallon bucket with soapy water. Then, shake flowers suspected of containing beetles over the bucket. The beetles will fall in and drown.

Hoplias are attracted to white, so try this trick: Fill white buckets (preferably 5-gallon) or other large containers with water; the important thing is that these containers are white. Add a few drops of detergent to the water to break surface tension. Place these beetle traps at several locations among your rose bushes. Thinking it's a giant white bloom, hoplias will fly into the white bucket and meet a watery death.

The other solution? Stick to red roses; hoplias don’t like red.

For more information on hoplia beetles, check out the UC Integrated Pest Management pest notes at: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7499.html

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GENERAL GARDENING

An article about gardening.

Keywords:

UCCE master gardeners hoplia beetles gardening Sacramento integrated pest management insecticides pest damage pests roses spring flowers UC IPM

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Garden checklist for week of Aug. 2

Get out early in the morning and monitor your garden’s moisture needs. Deep water and add temporary shade structures for plants that are feeling a little burned. In particular, protect developing peppers and eggplant.

* Put off fertilization until this heat passes; plants need to concentrate on hydration instead of growth.

* Harvest tomatoes, beans, squash, pepper and eggplants to prompt plants to keep producing. Give your plants a deep watering twice a week, more if planted in containers.

* Watch out for caterpillars and hornworms in the vegetable garden. They can strip a plant bare in one day. Pick them off plants by hand in early morning or late afternoon.

* Mulch can be your garden’s best friend – it conserves moisture while blocking out weeds. But don’t let mulch mound around stalks, stems or trunks. That can promote rot.

* Pinch off dead flowers from perennials and annuals to lengthen their summer bloom.

* Pick up after your fruit trees. Clean up debris and dropped fruit; this cuts down on insects and prevents the spread of brown rot.

* Prepare for a fall full of flowers by paying a little extra attention to your garden. Cut off spent blooms from roses, annuals and perennials. Roses will rebloom about six to eight weeks after deadheading.

* Indoors, start seedlings for fall vegetable planting, including bunching onion, cabbage, broccoli, cauliflower, kale, radicchio and lettuce.

* Sow seeds of perennials in pots for fall planting including yarrow, coneflower and salvia.

* In the garden, direct seed beets, carrots, leaf lettuce and turnips. Make sure to keep seeds and seedlings consistently moist.

* Plant potatoes.

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