Japanese Beetle

June 18, 2018
  • Japanese Beetle

Japanese Beetle

The Japanese beetle is a common species of beetle originating in Japan. They were introduced to the United States in 1916, after being accidentally brought into New Jersey. Unlike Japan, where Japanese beetles have natural predators, in the US they tend to feed off of whatever plants they wish.

Adults emerge in June, July, and August. They feed off of over 300 species of plants and will mate in turf areas, leaving eggs wherever their heart desires. They are most active when the temperature is warm and there is little to no wind.

Treatment Options

There are various options to combat Japanese beetles in adult form. These include hand picking, Neem oil, or simply choosing the right plants. Although Japanese beetle adults can tear up rose blooms and fruit-tree leaves pretty well each July, that damage is mostly cosmetic. After a few weeks of feeding and egg-laying, the adults die, and the plants grow new leaves.

Hand picking

First of all, the most inexpensive solution to killing Japanese beetles is to hand pick them off of the plants, drop them into a bucket of water filled with soap. With this approach, you are ensuring each beetle is taken care of.

Neem Oil

Neem is natural pesticide found in the seeds from the neem tree. These trees are native to the Indian subcontinent; to be found in India, Nepal, Pakistan, Bangladesh, Sri Lanka, and Maldives.

The active component is called Azadirachtin; its purpose is to repel and kill pests. The remaining component is called clarified hydrophobic neem oil.

Choosing The Right Plants

Japanese beetles feed off of the leaves of 300 + various plants and trees, but they tend to avoid certain species. When choosing new foliage, consider the following choices.  Replacing plants that attract Japanese beetles with those that deter them can help you avoid the problem in the first place.

  • American Elder
  • Begonias
  • Boxelder,
  • Dogwood
  • Firs
  • Holly
  • Hydrangeas
  • Junipers
  • Lilac
  • Magnolia
  • Oaks
  • Redbud
  • Rhododendron
  • Tulip tree
  • White oak

What to avoid.

Two solutions include what to avoid. In order to prevent the increase of Japanese beetles, avoid the use of Japanese Beetle Traps. Also, you can simply avoid the planting of vulnerable plants that attract Japanese beetles.

Do Not Use Japanese Beetle Traps

Putting out a Japanese beetle trap may seem like the simplest solution, but can make matters worse. Japanese beetles may be caught in the traps, but they can still release pheromones to attract other beetles. This increases the amount of beetles to combat. Research done at University of Kentucky has found that each Japanese beetle bags/traps collect up to 2000 Japanese beetles but attract up to 429,000 Japanese beetles over a 10 day period.

Vulnerable Plants to Avoid

The following plants and trees attract Japanese beetles. Avoid planting any of these if you want to avoid Japanese beetles. If you have these species, monitor them and treat using one of our recommended solutions.

  • American Linden
  • Apple
  • Apricot, Cherry, Peach, and Plum
  • Birch
  • Crabapple
  • Japanese maple
  • Norway maple
  • Rose