The Idaho State Department of Agriculture is in the second year of a program aimed at eradicating Japanese beetles, which started multiplying in the Boise area in 2011.
The treatments use granular formulations of common insecticides. The first treatment of Acelepryn was applied to turf and lawn-covered areas in mid-May to prepare the grass to kill grubs as soon as they begin feeding. In mid-July the same areas will be treated with a granular formulation of Merit to kill feeding grubs that escape the initial treatment or later-hatching grubs.
About $450 million is spent in the United States each year to keep the beetle populations down, said Paul Castrovillo, pest survey and detection manager for the Idaho State Department of Agriculture. The beetles attack foliage, flowers and fruits of more than 300 different ornamental and agricultural plants, leaving them skeletonized. The larvae or grubs feed on grass roots, like lawns, golf courses and parks, causing costly damage.
“Grubs chew the grass up so bad that in the East, the grass will just pull away like a piece of carpet,” Castrovillo said.
The Japanese beetle has been a problem in the eastern United States since 1916 and is considered one of the most aggressive invasive insect pests in the United States. Until recently, Idaho and most of the neighboring states resided in a protected zone and trapping and beetle detection efforts yielded almost no beetles. The state has been testing for Japanese beetles since the early 1990s, and found one or less each year until 2012, Castrovillo said.
But in 2012, 61 of the beetles were captured in Boise and in 2013, 2,999 beetles were captured, spurring the first year of treatments to residential and commercial properties. More properties were treated in 2013.
This year, about 500 residential and commercial properties near Warm Springs and West State Street, and on the Boise State University campus, are being treated, as well as some other areas in the city. The Idaho eradication program for Japanese beetles is modeled after a program in Orem, Utah that started treatment in 2007 after a rapid infestation. Last year, only one beetle was trapped there, Castrovillo said.
The state has budgeted about $400,000 for Japanese beetle eradication this year, said Lloyd Knight, administrator of the division of plant industries at ISDA. Knight said the department is concerned about the effects on landscaping, and also on agriculture.
The goal of the treatment is to make sure the beetles don’t spread to other verdant areas like Boise. They can’t survive in the dry foothills, said Castrovillo.
“Japanese beetles can easily be transported to a similar oasis from Boise,” he said. “If we didn’t do anything, ten years from now we would be buried in beetles.”