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Attack of the hoplia beetles

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:


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Dig In: Garden Checklist

For week of Dec. 3:

Make the most of gaps between raindrops. This is a busy month!

* Windy conditions brought down a lot of leaves. Make sure to rake them away from storm drains.

* Use those leaves as mulch around frost-tender shrubs and new transplants.

* Rake and remove dead leaves and stems from dormant perennials.

* Just because it rained doesn't mean every plant got watered. Give a drink to plants that the rain didn't reach, such as under eves or under evergreen trees. Also, well-watered plants hold up better to frost than thirsty plants.

* Prune non-flowering trees and shrubs while they're dormant.

* Clean and sharpen garden tools before storing for the winter.

* Brighten the holidays with winter bloomers such as poinsettias, amaryllis, calendulas, Iceland poppies, pansies and primroses.

* Keep poinsettias in a sunny, warm location. Water thoroughly. After the holidays, feed your plants monthly so they'll bloom again next December.

* Plant one last round of spring bulbs including daffodils, crocuses, hyacinths, anemones and scillas. Get those tulips out of the refrigerator and into the ground.

* This is also a good time to seed wildflowers such as California poppies.

* Plant such spring bloomers as sweet pea, sweet alyssum and bachelor buttons.

* Late fall is the best time to plant most trees and shrubs. This gives them plenty of time for root development before spring growth. They also benefit from fall and winter rains.

* Lettuce, cabbage and broccoli also can be planted now.

* Plant garlic and onions.

* Bare-root season begins. Plant bare-root berries, kiwifruit, grapes, artichokes, horseradish and rhubarb. Beware of soggy soil. It can rot bare-root plants.

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