| Amy |
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| #1 |
This summer, I have found Japanese Beetles in my Roseville yard, my parent's farm in Chanhassen, and Swede Hollow park. I do not remember seeing them in past years.
Is there an outbreak?
How much damage can they cause to my yard trees?
I found this link to UM Extension info, but it did not comment on potential damage.
http://www.extension.umn.edu/distribution/horticulture/DG7664.html
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| Jeff Hahn |
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| #2 |
Numbers of Japanese beetles had been at low levels as they are a relatively new pest here. But they have been steadily increasing over the last 5 or 6 years in the Twin Cities. They have also been spreading out and infesting areas in the state where they really have not been found before. Even with that said, there overall numbers are still not as abundant as has been found in the eastern U.S.
The potential damage they can cause depends on how abundant they are. They can cause anywhere from slight to complete defoliation. Of course trees can generally tolerate insect feeding even when it is severe. If you are concerned about Japanese beetle damage, keep an eye on your landscape plants when Japanese beetles are active, July through September, and treat if necessary.
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| Steve Katovich |
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| #3 |
Jeff would have a better feel for the populations trends in Minnesota for Japanese beetle. My impression is that over the past 10-15 years they have become more widespread and common though I would not rate them as a significant pest of most Minnesota landscapes at this time. Prior to the early 1990's you would have had great difficulty finding this insect in Minnesota.
So, yes they are becoming more abundant and common in the state. I generally view Japanese beetle as a turf and garden pest more than a tree pest, the larval stages feed on the roots of grasses and other plants. The adults do leaf feed on a wide variety of plants, roses and grapes are two very common hosts for adult beetles to feed on. I have seen them feed readily on American elm and linden leaves. I believe birch, many of the crab apples, plums and other Prunus species are also preferred hosts. But, here in Minnesota I have not seen any tree defoliation caused by Japanese beetle.
So, I would not be overly concerned about finding an occasional Japanese beetle. If you begin to see groups of them clumping on certain landscape plants, probably in late June through July, then you may have some valid concerns. There are a few control tactics that a homeowner may consider. I would check
http://www.ca.uky.edu/ENTOMOLOGY/entfacts/ef451.asp
or
http://ohioline.osu.edu/hyg-fact/2000/2001.html
-Steve-
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Steven Katovich, Ph.D.
USDA Forest Service NA SPFO
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| Anna | |
