Do Japanese Beetles Stop Attacking Trees Once Trees Mature?

7 years ago

Hi all,

I was wondering if the Japanese Beetles will stop attacking our young trees once they reach a certain amount of maturity? Or, will they continue to eat the leaves on the canopy of our trees even when the trees are 15-20 years old?

Four young trees we planted in our yard seem to get infested with Japanese Beetles every year around this time (cherry, oak, sycamore and apple). They especially seem to love the leaves of the Stella Cherry and Red Oak trees.

For the last three or four years I have applied Bayer Advanced Tree and Shrub Protect and Feed, but it doesn't seem to do anything to prevent them from coming back. Once I spot the Japanese Beetles, I apply Neem oil to the leaves followed by Sevin dust. Sevin dust sticks to the trees' leaves after I apply Neem oil, and this combo seems to control them well. However, it is somewhat expensive and a real pain. Heavy rains will wash these chemicals off, requiring a new application every few days.

Thank you for your help.

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Comments (5)

User
7 years ago
I can't answer your question about age of trees but highly doubt that will make any difference other than that a mature tree has much more volume of crown and can withstand more damage, generally speaking.

One thing that helps with Japanese beetles is to stop killing your birds with all that poison. Many common birds eat both the larvae and beetle (Popillia japonica) stage which greatly decreases their population. The link below explains this and other preventative measures.

http://mghc.org/2010/06/17/japanese-beetles-start-preventing-next-years-crop-today/

You may have to use netting until you get the population under control.
whaas_5a
7 years ago
Japanese Beetles don't discriminate. As Bill mentioned the older mature trees need larger populations to be effected. I can tell you my line of say 60 year old Tilia americana where notably thinner as I could see through the canopy to the farm field after being attacked for well over a month. In some cases the canopy appears brown.

More birds this year for some reason. The JB attack this year seems to have subsided at this point until the next crop arrives. Coincidence? I hope not I wish more birds would visit me. I will continue to add trees and evergreens but summer year after year continues to bit slap me with drought.
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bengz6westmd
7 years ago
Depends, but I remember J beetles doing a number on a large European horsechestnut.
User
7 years ago
Seems to me, Japanese beetles like hot sunny weather. So if you're been having a lot of that kind of weather with mainly sun, it's like throwing a party for them.

UH, do some google searches for 'plants that repel JB', you might find something there you can do in that area.
arbordave (SE MI)
7 years ago
last modified: 7 years ago
Japanese beetles prefer feeding on foliage in full sun, and the upper crowns of mature trees generally suffer more damage than the lower portions.

"They especially seem to love the leaves of the Stella Cherry and Red Oak trees" That's interesting since Red Oak is not a preferred host for JB. I have plenty of JB's here but I don't think I've ever seen a JB on the 2 red oaks in my yard.

"One thing that helps with Japanese beetles is to stop killing your birds" I agree that we shouldn't be killing birds, but birds alone probably don't have a major impact when JB numbers are high.

Weather factors can have a significant impact, like very dry conditions after egg laying (mid to late summer), or very low soil temperatures in winter. These factors seem to have resulted in somewhat lower JB numbers in recent years at my location, although numbers may be higher this year since we had adequate rainfall mid to late summer last year. Lots of JB activity out there today, currently 95F and sunny.