While the defoliation of beloved plants can be extremely frustrating, it is important to note that not all yards in a given neighborhood are equally effected by the annual Japanese Beetle invasions. Being familiar with the top 6 approaches to preventing Japanese Beetles from coming into your yard can put you ahead of the game the next time the dreaded season comes around.
Alter Plant Selection
Certain trees, shrubs and plants are more palatable than others to the voracious Japanese Beetles. If your main goal is to simply keep the beetles out of your yard, the simplest solution is to remove the desired food source from your yard.
Whether you are planning a new landscape or looking to alter what is already there, you can select plants that are best at keeping the annoying beetles away. Instead of planting American Linden, fruit, or Birch trees, select Ash, Boxwood or Dogwood. Instead of roses, you can choose Magnolias, Hemlock, or a redbud tree.
In some cases, you may want to keep the plant and also protect it from the beetles. In such a case, there are other options besides uprooting the plant itself.
Cover Susceptible Plants
Typically the Japanese Beetle heavy foraging season is relatively short. If you are looking to protect some roses, fruit bearing trees, or other plants manageable in size, you can select certain soft or wire mesh covers for them.
When installing, ensure that the gaps are small enough to keep the beetles out. Also keep in mind that Japanese Beetles can fly so the covering has to be completely over the plant.
Certain products (neonicotinoids.are the most commonly used products in this regard) can be injected directly into the tree or plant in question. Typically, it can also be applied to the root system of the plant in a manner that will get absorbed up into the plant. These treatments can last 6-18 months in different kinds of plants and make the treated plant less desirable and/or lethal to the feeding beetles.
The downside to systemic treatments is that the product can become present in the flowering portion of the plants which can be harmful to pollinators such as honey bees.
Certain essential oils have been found to be effective in repelling or at least reducing the attractiveness of certain plants to Japanese Beetle populations. Some of these include anise, bergamont mint, cedarleaf, dalmation sage, and terragon. Whenever you are working with essential oils, it is important to understand the type of plant you are using and how that oil may effect it. You don’t want to trade the situation of a beetle eating your beloved plant to directly killing it or stunting its growth with an oil. If unsure, it is always best to test it in a small area to observe the effects. In addition to the above mentioned oils, the cocktails of wintergreen oil mixed with ginger and peppermint and citronella oil mixed with ginger have shown effective reduction in plant attractiveness in certain situations.
Be Ready to Adjust
Just because something worked last year does not mean it will be the same this year. Be vigilant with regard to the effectiveness of your chosen method. Adjust as needed and keep ahead of the beetles as much as possible.