Japanese Beetles: the Next Chapter

This article was written by Gail Griffin, Extension Master Gardener℠ Volunteer in Lee County.

If you were plagued by the scourge of Japanese beetles earlier this summer, you were not alone.  Multitudes of these beetles could be found devouring leaves and blooms of everything from roses to Crape myrtles to fruit trees, leaving skeletal remains behind that once resembled plants. By August, adult females have laid their numerous eggs and completed their life cycle.  For those who thought the carnage was over, welcome to phase two.

Adult Japanese beetles prefer damp soil to burrow in and deposit their eggs.  After a few weeks, the hatched eggs feed on roots of grasses and shrubs and begin the larval stage as grubs.  It is at this point where damage to turf is most noticeable. Large patches of dead grass can be the first indicator.  Rolling back the turf in suspected areas will reveal a number of white, "c"-shaped grubs with yellow-brown

Japanese beetle grubs

heads.  Control is usually recommended if there are ten or more grubs
per square foot. If treatment is needed, it will be more successful at this stage when the grubs are smaller in size and closer to the soil surface.  As temperatures fall, they dig deeper into the soil and hibernate until the spring.  When the weather warms, they begin their ascent closer to the surface and emerge as adults and continue their feeding frenzy on our landscape.

Control of Japanese beetles is an ongoing challenge.  They can fly onto your property from other areas causing them to become a pestilence and a pestilence will find you. Think Ernest T. Bass.

Planting non-susceptible plants such as hollies, junipers, and azaleas can be a good alternative.  Traps are not generally useful and can end up attracting more beetles. Sweeping them away from plants into a container of soapy water can be effective, but must be done regularly and is often unattainable. Chemical control can be helpful if applied at the time of discovery and if label instructions are followed.  Be sure to consider our pollinators when using insecticides. Using liquid or granular formulations instead of dusts can help limit transfer to
bees and other beneficial insects. For recommendations, contact your local N.C. Cooperative Extension office or see our Japanese Beetle publication. Don't despair.  Depending on conditions, the populations of Japanese beetles are less in some years than they are in others.  Shoot for the good feeling.

Gail Griffin is an Extension Master Gardener Volunteer in Lee County.