Threat of voracious Japanese beetles persists

Japanese beetles on a rose plant.
Japanese beetles on a rose plant. California Department of Food and Agriculture

Just one is too many.

The find of a single Japanese beetle in June means at least three more summers of orchestrated pest fighting in the Sacramento suburbs.

But when it comes to these voracious insects, officials say, the stakes are too high to surrender any California turf, including drought-parched lawns in Carmichael or Fair Oaks.

State and Sacramento County agricultural departments still are aggressively combating the destructive bug, considered the nation’s No. 1 turf pest and a major threat to many crops – including grapes, citrus and stone fruit – as well as a wide range of ornamental plants. They attack plants above and below ground. The adult beetles eat leaves; their burrowing larvae, or grubs, gobble roots.

Nationwide, the war on Japanese beetles costs more than $460 million a year, according to the U.S. Department of Agriculture. The annual damage caused by just the lawn-munching larvae is estimated at more than $234 million.

But much more is at stake, particularly in California, which so far has been spared a beetle barrage. A widespread infestation could cripple the state’s $40 billion agricultural industry, say state officials. California’s $5.2 billion grape harvest is at particular risk from Japanese beetles, which love to feast on grape leaves. These ever-hungry insects also have an incredible appetite for strawberries, asparagus, corn, walnuts, apples, peaches, plums, oranges and dozens of other crops.

So far, these destructive beetles have been found only in residential neighborhoods, not farmland. That’s put the brunt of containment efforts on homeowners, who have endured spraying programs for five years.

Motivated by beetles more than drought, Carmichael resident Ellen Sward decided to take away the pest’s potential nesting area; she’s ripping out her lawn.

“I’ve already pulled out all the plants they sprayed (for beetles), so there’s nothing they like to eat,” said Sward, whose home has been part of the treatment area since 2014. “And if there’s less grass, there will be fewer places for pregnant beetles to burrow and lay eggs.”

Triggered by a total confirmed find of 17 Japanese beetles since 2011, the local eradication campaign has been expensive. According to state figures, the state Department of Food and Agriculture spent more than $2.7 million for Japanese beetle eradication since that first sighting in Fair Oaks. That includes statewide trapping and a third treatment program in Sunnyvale.

After citizen requests and scientific review, the anti-beetle ground campaign has scaled back its chemical warfare in Fair Oaks and Carmichael, where beetle spraying and trapping have become a summer ritual.


Rather than spraying a wide range of possible host plants with three highly toxic chemicals, state Food and Agriculture Department pest experts treated only lawns in late May and June with drenches of liquid Acelepryn, considered a less toxic alternative. Those neighborhood applications are now complete with the exception of Carmichael’s Jesuit High School, which is scheduled to have its lawns treated next week, according to state Food and Agriculture spokesman Steve Lyle.

“We’ve accepted for now, somewhat gratefully, a reduced-risk chemical,” Sward said. “We’re realists.”

That change of tactics came after several residents, including Sward, demanded less toxic chemicals be used on their home landscapes. Under the slogan “Stop The Spray,” they protested the program while reluctantly participating.

“Some homes in Fair Oaks were sprayed more than 20 times,” Sward said. “The spray trucks were in our (Carmichael) neighborhood almost every day last summer.”

In past summers, the beetle fighters sprayed imidaclophrid, a neonicotinoid that’s deadly to honeybees and many other insects; carbaryl, a likely human carcinogen; and cyfluthrin, which is highly toxic to fish.

“People lost lots of bees, but also frogs and lizards disappeared,” said Sward.

According to label directions, soil treated with these chemicals should not be used for growing vegetables for a year, she added.

“All my ladybugs are gone,” said Fair Oaks’ Patty Larsen, whose home has been in the treatment area since 2011. “For the people (whose homes were) being sprayed, it’s really upsetting. It really makes you feel like it’s overkill.”

State Food and Agriculture Department spokesman Lyle, however, said the threat was too serious to allow any exceptions.

“While some of our programs can accommodate opt-outs, the eradication program for this invasive species cannot,” Lyle said.

Checked weekly, traps now fan out over a 3.5-mile radius around both treatment areas, Lyle said. Those areas, which extend 200 meters from each beetle find, include 41 homes in Fair Oaks and 249 in Carmichael.

No beetles have been found in Fair Oaks since 2014, but that area will remain under observation and monitoring through 2017, according to Ramona Saunders, Sacramento County’s deputy agricultural commissioner.

“If there are no finds, the (beetle in that) area will be considered officially eradicated,” Saunders said.

The state’s three-year observation time is due to the pest’s life cycle. Japanese beetles spend most of their lives underground as larvae or grubs, eating roots for months. With warm weather, the beetles emerge as winged adults in June. The adults attack leaves, munching away until the skeletonized foliage has only lacelike veins. With a 40-day lifespan, the female adults lay about 40 to 60 eggs, usually in the top two inches of irrigated lawn where their inch-long white grubs will overwinter.

Because these beetles spend so much of their life cycle underground as larvae, the new eradication effort focuses on that grub stage, concentrating on lawn treatments.

Complicating eradication efforts are cases of mistaken identity. Half-inch long with bronze-colored wings, Japanese beetles resemble other beetles with iridescent wings. Likewise, their inch-long white grubs look like other beetle larvae that live in lawns.

Fig, hoplia and June beetles – which are much more common in the Sacramento area – all can be mistaken for Japanese beetles. That causes confusion, especially when gardeners go online searching for possible identifications.

If anyone sees a suspected Japanese beetle, they’re asked to report it to their county agricultural office or the state food and agriculture’s exotic pest hotline, officials say.

Japanese beetles are not a new threat. This summer marks the 100th anniversary of the first confirmed Japanese beetle sighting in the United States. One of the shiny copper-toned pests was discovered in New Jersey in 1916, accidentally imported from Japan in an order of iris bulbs, according to reports.

From that foothold, Japanese beetles spread throughout the East Coast and into the Midwest, wreaking havoc on rose gardens and golf courses as well as crops.

Japanese beetles were first reported in the Sacramento area in 1961 and 1962, when 449 total adult beetles were trapped in Capitol Park and near the Crocker Art Museum. A massive eradication effort stopped that threat.

The beetle was seen again in 1983 in Orangevale, provoking diazinon spraying of almost 500 homes. More than 40 homeowners refused to cooperate, forcing state agriculture officials to obtain warrants to spray their property. Two property owners were arrested for trying to block spraying.

No Japanese beetles were seen again locally until 2011, when two beetles showed up in Fair Oaks, followed by a second confirmed infestation in Carmichael last year.

As their name implies, the beetles are native to Japan, where they’re not considered a major pest. Natural predators in their native habitat keep this beetle in check.

But in North America, Japanese beetles escape most of their predators in a land of abundant irrigated lawn, their favorite nesting ground.

“One of the reasons they’re so bad is that the adults and the larvae both do damage,” explained Darren Van Steenwyk, technical director for Lodi-based Clark Pest Control. “Normally, with a lot of insects, one stage or the other will do damage but not both.”

In addition, the adults and larvae attack different plants in different ways, with more than 300 plant species believed to attract Japanese beetles, according to the USDA.

“Most insects specialize in eating one thing or a limited range (of plants), Van Steenwyk said. “Japanese beetles are a broad-spectrum pest.”

Although they can fly, Japanese beetles tend to move to new areas by hitchhiking on vehicles or moving hidden in nursery stock. That’s kept local residents and pest experts especially vigilant this summer.

“We don’t expect to see them,” Van Steenwyk said. “But if we do, we’ll contact the county right away.”

Debbie Arrington: 916-321-1075, @debarrington

Have you seen a Japanese beetle?

If you see a Japanese beetle in your garden, report it to the Sacramento County Agricultural Commissioner office, 916-875-6603, or the California Department of Food and Agriculture Exotic Pest Hotline, 800-491-1899.

Plants most at risk:

Japanese beetles are the No. 1 turf grass pest in America. Their grubs gobble roots under lawns. But the adult beetles have a wide-ranging appetite.

Japanese maple

Crape myrtle


Stone fruit (peach, plum, apricot, pluot, cherry etc.)

Pin oak



Black walnut

Lombardy poplar


These herbaceous plants are at high risk from Japanese beetles:



Sweet corn








How to spot a Japanese beetle

Japanese beetles, almost unseen in California, look similar to other beetles common in the Sacramento area, particularly the smaller hoplia beetle and the larger fig beetle. Grubs of June bugs look like Japanese beetle larvae, too. Use size and location to tell them apart. And look for the hairs.

Advice from retired state entomologist Baldo Villegas:

Japanese beetle

Japanese beetle

Size: 3/8 inch by 1/4 inch wide.

Color: Body is all metallic dark green and only the wing covers are brown.

Location: Adult beetles eat foliage down to the veins. Grubs live in lawns just below the surface.

Baldo's tip: “There is a row of white hair tufts on the abdomen, and two larger tufts are very obvious in the back of the abdomen.”

Fig beetle

Fig beetle

Size: 1 inch long

Color: Metallic body. The wing covers are green and never metallic.

Location: Fig beetles like shade under fruit trees and often make a loud buzz. As adults, they can’t eat foliage, just damaged or fallen fruit. The grubs are large (about 2 inches long) and are generally found on the outer areas of a compost pile, never underground beneath turf grasses.

Baldo’s tip: “Fig beetles are common in the Sacramento area but they are much bigger than Japanese beetles. They lack the white hair tuffs on the sides of the abdomen and at the end.”

Hoplia beetle

Hoplia beetle

Size: 1/4 inch long and wide

Color: Light brown;never metallic green.

Location: They loveto eat rose flowers.

Baldo’s tip: “Hoplia beetles are squarish in shape. The wing covers are brown but are usually covered with light brown scales that look like dust. The underside of the body is brown and covered with light brown to silvery metallic colored scales.”

June bugs

June bug

Size: Under 1 inch.

Color: Dull metallic green wings, underside of body very shiny.

Location: Adults appear in June; attracted to rotting fruit.

Baldo’s tip: “Unfortunately there are some native June beetle grubs that look very similar to Japanese beetle grubs that are also found feeding in lawn and turf areas in California.”

Suspect grubs can be submitted for identification to the California Department of Food and Agriculture Plant Pest Diagnostics Center, 3294 Meadowview Road, Sacramento, CA 95832.

Get more info: ipm.ucdavis.edu

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