Good Questions: Japanese Beetles

By: Christina Timm

In our last blog we touched base on treating your lawn with Grub Beater to help prevent Japanese Beetles for next year. Opening up this conversation raised some great questions like:

Japanese Beetles Feasting on Rose Flower

Japanese Beetles Feasting on Rose Flower

Does it really matter if I treat my lawn for Japanese Beetles? If the neighbors don't, won't they just fly over and start the process all over again?

This is a really great question and makes a great point! However, there are a few factors to take into consideration. Female Japanese Beetles are looking for just the right type of soil/turf to lay their eggs. She's looking for large areas of turf in full sun that is well watered, so basically anyone's dream, lush lawn. Not everyone has this type of environment. In a more developed neighborhood trees provide shade that creates a non-ideal habitat for her eggs. On the other hand, it's not realistic to say she will never lay her eggs in the shade, it's just not ideal. Also, having a lawn in the sun requires upkeep that some people don't have time for. 

Another important factor is having plants that the Japanese Beetles love to feast on. There are over 300 species of plants that they enjoy, however not everyone has these in their yard or some are more affected than others. 

With this said, not every yard is affected by Japanese Beetles and some are more affected by others, depending on your lawn and the species of plants you have in it. It's important to remember that while they are feasting on your plants they are also mating, and soon after the females will lay their eggs. 

Did you know: The Japanese Beetle only lasts about 30 to 45 days.

So, should you treat your lawn for Japanese Beetles? It depends on how destructive the Japanese Beetles are in your yard. If you have plants that Japanese Beetles are most attracted like perennials such as American Linden trees, Apple or Crabapple trees, or Roses it would then be recommended to treat your lawn due to the size of these plants and the amount of beetles they can attract. Not to mention that they will most likely to be laying eggs in or near your lawn.  If you are already heavily affected by Japanese Beetles with your annual plants maybe avoid: Hibiscus, Dahlia, Canna, and Zinnia and instead try Dusty Miller, Begonias, Coleus, and New Guinea Impatiens.

What product should I use?

Honestly, it depends on your situation and how badly you are being affected. Japanese Beetle traps work great for hard to reach areas like in trees and out of control areas with mass quantities of beetles. The Japanese Beetle spray is great for manageable areas like shrubs, low growing perennials, and annual containers/beds. The Grub Beater granular is great as a preventative measure for next year if you are heavily affected and want to be proactive.

Here are 3 steps to approach your Japanese Beetle problem:


1. Japanese Beetle Traps: Use if you have a large quantity of beetles. We recommend you use for 2-3 days, then take it down for a week. The trap has attractants with potent pheromones that draws in the beetles, however you don't want to attract every beetle in the neighborhood. When trap is not in use place the trap in a Ziploc bag indoors.

2. Japanese Beetle Spray: Use in areas that are reachable. This works great on annual container gardens and beds that are manageable. It also helps to remove affected foliage/plant material before spraying to further decrease the population in your yard. 

Helpful tip: For a more natural alternative, knock Japanese Beetles into a dish of soapy water.

3. Grub Beater: Use as a defense for the future. Apply Grub Beater to your lawn using the proper protective wear and application rates for your area of lawn. A granular that can be dissolved by irrigating after spreading works best.  

Be sure to read and follow the label of any product you decide to use before application.

Japanese Beetle Damage on a Crab Apple Tree

Japanese Beetle Damage on a Crab Apple Tree

Where did Japanese Beetles come from in the first place?

Japanese Beetles are native to Japan where interestingly enough these beetles are not as destructive there as they are in the United States. In fact, they are not even considered to be pests. The biggest reason for this is the population. Japan is a smaller area that is heavily populated so if Japanese Beetles are looking for large areas of sunny turf to lay their eggs, they aren't going to find that in Japan. The United States, however, has many large expanses of turf to lay their eggs and re-populate.

Did you know: The first written evidence of the Japanese Beetle in the United States was in 1916 at a nursery in New Jersey. It was thought that the beetle larvae entered on a shipment of iris bulbs.

The Japanese Beetle can be very destructive, feasting on certain plants to the point of creating a skeleton. It's important to remember that when treated properly trees, shrubs, and perennials can maintain a strong structure and survive some Japanese Beetle destruction. 


Here is a link for more information on Japanese Beetles from the University of Minnesota.

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