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Dreaded Japanese beetles found at two Sacramento County sites

Japanese beetles are serious destructive pests. Hundreds of traps are now out in a 49-square-mile area. (Photo courtesy Sacramento County Agricultural Commission)

Trapping follows discoveries in Rancho Cordova, Arden-Arcade

America’s No. 1 turf pest is trying to invade Sacramento – again. But much more than lawn is at stake. This bad bug is a major threat to California agriculture, too; it can destroy more than 300 crops including wine grapes, citrus and stone fruit. And it really likes roses, too.

The dreaded Japanese beetle has been discovered in two locations in Sacramento County, triggering a massive trapping campaign.

According to the Sacramento County Agricultural Commissioner and the California Department of Food and Agriculture, a total of 19 Japanese beetles – eight in Arden-Arcade and 11 in Rancho Cordova – were recently found. Those initial detections were confirmed June 4, the county announced Tuesday.

This week, state and county staff placed hundreds of green plastic traps over a 49-square-mile area. Those beetle traps will be monitored daily within a mile of the initial sightings; weekly farther away.

Most of the traps are placed near Japanese beetles’ favorite domain – lush green lawn. Its grubs devour the roots of turf grasses, causing an estimated $250 million in damage annually, according to the USDA.

As their name implies, Japanese beetles are native to Japan, where they are not considered a pest. Natural predators keep their numbers in check. But in North America, Japanese beetles have found an unlimited buffet with no predators to stop them. And they eat their entire lives; below ground as larvae on roots, and above ground as adults on fruit and foliage, which they skeletonize.

“Among the plants most commonly damaged are apple, pears, cherries, corn, grapes, roses and turfgrass,” said the county’s announcement. “Adults leave behind skeletonized leaves and large, irregular holes. The grubs develop in soil, feeding on the roots of various plants and grasses and often destroying turf in lawns, parks, golf courses and pastures.”

Sacramento County residents are urged to be on the lookout for this pest. The Arden-Arcade discovery was made near the intersection of Watt and Whitney avenues.

According to the CDFA website, these are the first Japanese beetles to be detected in Sacramento County neighborhoods since 2017 when one beetle was trapped in Fair Oaks.

The adults appear in June and July before tunneling back underground to lay eggs. Those eggs hatch in late summer and the larvae spend the next nine months eating roots.

This is a fig beetle or green fruit beetle,  which is sometimes
mistaken  for a Japanese beetle. But it's nearly twice as large as the
invasive pest -- up to 1-1/3 inches long. (Photo courtesy UC IPM)

About a half-inch long with bronze iridescent wings, Japanese beetles look a lot like other beetles common in Sacramento in early summer, including fig, hoplia and June beetles. But the Japanese beetle is a lot more destructive. Among the trees at highest risk: Japanese maple, crape myrtle, apple, stone fruit (peach, plum, apricot, pluot, cherry etc.), pin oak, linden, birch, black walnut, Lombardy poplar and willow.


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Dig In: Garden Checklist for week of April 7

The warm wave coming this week will shift weeds into overdrive. Get to work!

* Weed, weed, weed! Whack them before they flower.

* Mulch around plants to conserve moisture and control weeds.

* Smell orange blossoms? Feed citrus trees with a low dose of balanced fertilizer (such as 10-10-10) during bloom to help set fruit. Keep an eye out for ants.

* Apply slow-release fertilizer to the lawn.

* Thoroughly clean debris from the bottom of outdoor ponds or fountains.

* Spring brings a flush of rapid growth, and that means your garden is really hungry. Feed shrubs and trees with a slow-release fertilizer. Or mulch with a 1-inch layer of compost.

* Azaleas and camellias looking a little yellow? If leaves are turning yellow between the veins, give them a boost with chelated iron.

* Trim dead flowers but not leaves from spring-flowering bulbs such as daffodils and tulips. Those leaves gather energy to create next year's flowers. Also, give the bulbs a fertilizer boost after bloom.

* Pinch chrysanthemums back to 12 inches for fall flowers. Cut old stems to the ground.

* From seed, plant beans, beets, cantaloupes, carrots, corn, cucumbers, melons, radishes and squash. Plant onion sets.

* In the flower garden, plant seeds for asters, cosmos, celosia, marigolds, salvia, sunflowers and zinnias. Transplant petunias, zinnias, geraniums and other summer bloomers.

* Plant perennials and dahlia tubers for summer bloom. April is about the last chance to plant summer bulbs, such as gladiolus and tuberous begonias.

* Transplant lettuce and cabbage seedlings.

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