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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 March 26:

Sacramento can expect another inch of rain from this latest storm. Leave the sprinklers off at least another week. Temps will dip down into the low 30s early in the week, so avoid planting tender seedlings (such as tomatoes). Concentrate on these tasks before or after this week’s rain:

* Fertilize roses, annual flowers and berries as spring growth begins to appear.

* Knock off aphids with a strong blast of water or some bug soap as soon as they appear.

* Pull weeds now! Don’t let them get started. Take a hoe and whack them as soon as they sprout.

* Prepare summer vegetable beds. Spade in compost and other amendments.

* Prune and fertilize spring-flowering shrubs after bloom.

* Feed camellias at the end of their bloom cycle. Pick up browned and fallen flowers to help corral blossom blight.

* Feed citrus trees, which are now in bloom and setting fruit.

To prevent sunburn and borer problems on young trees, paint the exposed portion of the trunk with diluted white latex (water-based) interior paint. Dilute the paint with an equal amount of cold water before application.

* Cut back and fertilize perennial herbs to encourage new growth.

* Seed and renovate the lawn (if you still have one). Feed cool-season grasses such as bent, blue, rye and fescue with a slow-release fertilizer. Check the irrigation system and perform maintenance. Make sure sprinkler heads are turned toward the lawn, not the sidewalk.

* In the vegetable garden, transplant lettuce and kale.

* Seed chard and beets directly into the ground.

* Plant summer bulbs, including gladiolus, tuberous begonias and callas. Also plant dahlia tubers.

* Shop for perennials. Many varieties are available in local nurseries and at plant events. They can be transplanted now while the weather remains relatively cool.

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