Japanese Beetle Update – June 2019

By Jim Ross

Japanese beetle is an invasive plant pest that was detected in the lower mainland of British Columbia in 2017.  This voracious eater can significantly damage plants in the landscape including small fruit, vegetables, orchards, nursery plants and agricultural crops.  Although, it lays its eggs in turf, it is not thought to be a significant feeder on above ground turfgrass plant parts.

Female adults lay eggs soon after they emerge from the pupae stage (expected to be June 15 this year).  Eggs hatch within two weeks and begin to feed on roots of turf throughout the summer.  Larva will overwinter as the final instar stage by burrowing further into soil to avoid cold temperatures.  According to research information temperatures below -10C would kill the larva.  Much of the lower mainland and Vancouver Island never see temperatures this low. 

The larvae feed on the roots of grasses, which can result in wilting and yellowing of turf.  However, most of the damage that occurs on turf during the larva stage is mainly as a result of birds and animals foraging for the larva.  In very high infestations, dead patches of turf can develop which can create safety issues for athletes using impacted sports fields.

Surveying for the beetle began in 2010 and has been conducted annually since that time.  In 2017, 958 beetles were detected, most of which were found in the False Creek area of Vancouver.  In 2018, the population increased to over 8,000 beetles, which was expected. For more information go to: 2018 British Columbia Japanese beetle survey report - Canadian Food Inspection Agency 

A plan was put in place to control the further development of the population which included pesticide spraying and containment of potentially infested turfed areas in the regulated area.  Pesticide spraying of the insecticide, Acelepryn, began in 2018 prior to the emergence of the adult beetle.  This pesticide application was applied to all turfed areas within the regulated area with the thought that populations would decrease in 2019.  This year, as of June 10, all public lands in the high risk areas had been sprayed and treatment on private lands was continuing.  The eradication program, which is managed by the Canadian Food Inspection Agency, is intended to go on for at least three years.

Portland, Oregon has also had a recent infestation of Japanese beetle albeit one year earlier than BC.  The first year of treatment was 2017, which served to reduce the adult populations to just over 17,000 collected adults, a reduction of 34%.  This year will be an important measuring stick for BC as the first year of pesticide application was 2018.  Trapping of adults will take place throughout the summer and the reduction will be assessed in the fall.

For the first time, a biocontrol, bacillus thuringiensis galleriae, (or Btg) is available as a foliar spray for adult control.  Unfortunately, it is available only in commercial sizes and is not available as ‘Home & Garden’ packs.

For more information on Japanese beetle, sign up for the weekly newsletter from the BC Landscape and Nursery Association at https://bclna.com/japanese-beetle-updates/?utm_source=mailpoet&utm_medium=email&utm_campaign=Japanese+Beetle