KENNEWICK — A year after a few Japanese beetles were found in Pasco, the infestation of the highly destructive insects appears to have grown significantly.
More than 400 of the insects that can devastate grape crops, ruin lawns and strip roses of their leaves were caught in traps in Pasco this year, according to the Washington state Department of Agriculture.
Increased community participation and agreeing to free pesticide spraying is critical to eradicating the destructive beetles, say state ag officials.
If the infestation goes unchecked it would have serious trade and economic impacts in addition to direct damage to numerous crops grown in Washington, according to the department.
They were found mostly between Interstate 182 and the Columbia River, as well as south of East Lewis Street in East Pasco.
There also was a single Japanese beetle trapped across the Columbia River in Kennewick near Hawthorne Elementary School.
Officials with the Washington state Department of Agriculture are concerned, saying the number of trapped beetles increased in 2024 in central and eastern Washington communities along Interstate 82 from Yakima to Pasco.
The number trapped rose from nearly 19,700 last year to about 26,700 this year. Most were in the Grandview area, where 24,700 were trapped, followed by 1,500 in Wapato and then the 400 plus in Pasco.
Attacking Japanese beetle infestation
It has been providing free pesticide spraying to residents in areas where the beetles have been trapped, including in about a square mile area of Pasco, plus in Benton County west of Prosser near the Yakima County line and in Grandview, Sunnyside, Mabton and Outlook.
Landowners have to consent to the treatment each year, and only half of residents have given permission.
Participation in Pasco was slightly higher than in other areas in 2024.
“So far the level of community participation has only been enough to slow, but not stop or eradicate Japanese beetles from our state,” said Sven Spichiger pest program manager for the state Department of Agriculture, in a statement.
“If we are aren’t allowed to treat most of the properties in the infested areas, it is only a matter of time before it is too late to eradicate,” he said. “Then homeowners, gardeners and farmers will be left with the responsibility and expense of not only managing the pest but the burden of permanent quarantine regulations as well.”
The Washington state Department of Agriculture considered a quarantine for part of Pasco in 2024, but did not move forward with it after finding a dedicated drop site for yard debris in the mostly residential area was difficult.
However, in part of western Benton County and the Lower Yakima Valley a quarantine has been imposed that restricts moving yard waste, plants and soil out of the area. For five months of the year that includes cut flowers and all plants and plant cuttings.
The department is considering additional legal options to increase the number of treated properties, including seeking administrative warrants or an emergency proclamation.
“We hope that residents understand how important this is for our communities and will voluntarily sign up for treatment,” said Greg Haubrich, assistant director of the department’s Plant Protection Division. “But it is getting to the point where we may need to use all our legal options if we are to have any hope of eradicating this beetle.”
Treatment consent forms are being accepted now for 2025. People who were in a treatment area in 2024 can download a consent form at bit.ly/2025JapaneseBeetleForm for next spring.
Spraying of the larvicide Acelepryn would be done in the spring to kill larvae in the ground before they emerge.
The Department of Agriculture says the insecticide has a good safety record and is not a health risk for humans, pets, wildlife or beneficial insects such as bees, but that people and pets should avoid the treated area until it dries.
About Japanese beetles
The beetles, native to Japan and southeast Asia, are metallic green and brown and have little tufts of white hair on their sides as adults.
They overwinter underneath lawns or other soil and then emerge in June in the Mid-Columbia. They feed on more than 300 ornamental and agriculture plants, turning the plants into skeletons as they consume the foliage, flowers or fruit.
During their grub stage they also can attack grass roots, according to the U.S. Department of Agriculture.
“If Japanese beetles were to become established in Washington, it would pose a serious threat to gardens, parks and farms by destroying vegetation,” according to state ag officials.
Farmers could be prohibited from sending agricultural products out of the area.
The state of Oregon has estimated that if Japanese beetles were to become established there, the economic impact to its crops, commodities and other related businesses could be approximately $45.5 million.
