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How to control the Japanese Beetle
The Japanese Beetle is a very invasive species in North America. It does not do too well in it's native Japan but it thrives in the US and Canada. The white grubs live under ground and causes spots of brown grass and then no grass on the lawn. The adult beetle can ravage plants. You will find it eating holes into the leaves of roses, linden trees, elm trees, grape vines and almost any non toxic ornamental flower.
I used to think that Japanese Beetle can only be controlled effectively with biological methods while they are still living as grubs under the lawn. That is mostly true but it does
not mean you can do nothing once they have emerged as beetle.
The Japanese Beetle was introduced in the USA via a nursery in New Jersey and has spread from there across most of the states and to Canada. Here in Canada they emerge from the ground in
July and they are a problem until September. These beetles will attack almost anything but they have some preferences.
I have noticed that planting evening prime rose and meadowsweet will attract them to those plants and they will do much less damage to your other plants.
However you don't want them to thrive on the plants they are most attracted to. Instead you want to kill them there. You want a plant that has a comfortable height. Both evening prime rose and meadowsweet grow to about chest height. Evening prime rose likes dry soil and meadowsweet likes moist soil.
japanese Beetle are rather slow and clumsy pilots. They will not easily fly off. You can take some container (I just cut a milk carton open) fill it with a bit of water and put ONE drop of dish wash soap into it. This drop of dish wash soap will make it impossible for the beetles to swim on the water. The beetles will drown and die.
Now all you have to do is go to you evening prime rose and meadowsweet plants hold the container below a leave and push the beetles into it with the other hand. I do this twice a day: In the morning and in the late afternoon. This way you can collect hundreds of beetles and they will not bother to attack much of your other flowers and trees.
It's possible to buy commercial beetle traps for the Japanese beetle but evening prime rose and meadowsweet work very well and they come back every year once they are established. Evening prime rose is a biennial and meadowsweet is a perennial herb. If have 3-5 large evening prime roses and you check them every day the you will catch more beetle than with a commercial trap.
Here are some photos of the Japanese beetle. The yellow flower is evening prime rose. The plant with the white flowers is meadowsweet.
Using this method I have been able to reduce the number of Japanese Beetle over time. It takes about 2 years until you see a noticeable difference. They will still be there and you have to continue but you will notice that their numbers go down. They cause less damage on flowers and trees. Your lawn and your neighbors lawns will improve.
© 2004-2023 Guido Socher