Ada County Readies Japanese Beetle Pesticide

Posted at 10:46 AM, Mar 31, 2016
and last updated 2016-03-31 19:46:23-04

The Japanese Beetle eradication program by the Idaho Department of Agriculture is readying for what they hope will be their final round of pesticide applications to Boise lawns this spring and summer. They will begin the fourth year of the Japanese beetle eradication program in Ada County with the first pesticides scheduled to be laid in mid/late May. 

May's initial attack on the Japanese Beetle will be with Acelepryn.  The second treatment in July will be Imidacloprid.  The IDA says a one-two punch is needed because some bugs may be resistant to the first pesticide, so a second, different pesticide must be applied. 

The IDA says the pesticides are harmless to humans and pets.

The treatments will be ground applications of a granular insecticide on lawns in areas where Japanese beetles have been found. Only turf will be treated. No insecticide will be applied to vegetable or flower gardens, bushes or trees. That's because the grubs -- the Japanese Beetle larvae -- are under the lawn. They eat and kill the lawn grass.  Since that is also where they live, they are easy to destroy there. Once they are adults and can fly, they are much harder to eradicate.

The areas selected for treatment have been chosen based on data from Japanese beetle monitor traps set throughout the state. The yellow and green plastic traps -- which will be familiar to many Boise residents -- attract and capture Japanese beetles and are completely non-toxic. Beetles captured in the traps confirm a population is present. The number of beetles indicates the severity of the infestation.

Japanese beetle monitoring occurred without a major find for nearly twenty years.

In 2013, however, more than 3,000 beetles were detected in Ada County, which prompted the creation of the Japanese beetle eradication program. Successful treatments implemented in 2013 through 2015 reduced the beetle infestation by nearly 90 percent. Areas where beetles were captured last year will be designated for treatment again in 2016. Due to decreasing infestation density, the proposed 2016 treatment area will be reduced by approximately 50 percent of what was treated in 2015.

The Japanese beetle was first introduced to the United States in 1916 in plants imported from Japan. The insect is approximately one-half inch long, a shiny metallic green with copper-brown wing covers.

The beetles are considered one of the most aggressive invasive insect pests in the United States. If outbreaks are not treated, the insects reproduce and spread to new areas at a phenomenal rate. Their presence results in wide-scale negative economic impacts as well as environmental degradation due to massive damage to local vegetation and outcompeting native wildlife.

Homeowners are sent letters asking them for their permission to lay the pesticides. Homeowners may refuse but ultimately the IDA has the right to lay pesticide against the owner's permission.

For more information about the Japanese beetle, planned treatment areas, or if you think you have collected a specimen, please visit: or contact Paul Castrovillo at (208) 332-8627 or