Japanese Beetles Have Arrived on Wild Roses

2021 August 22

Back in 2014, I posted some pictures of japanese beetles that we found in the lower peninsula of Michigan, at Sandy’s parents’ place. At the time, I commented that I had not seen any of these beetles up here in the Keweenaw. Well, as of August 11, 2021, that has changed. Here are a bunch of them that I found on one of the “wild”[1] rosebushes on the Michigan Tech campus.


They were almost entirely on the rose blossoms. You might notice that a lot of the beetles are mating, which I suppose shows that roses are in fact romantic.


To some extent they were eating the petals of the roses, but mostly they appeared to be after the anthers (the part of the flower that produces polllen)


When I knocked the beetles off of that last blossom, they had stripped out pretty much all of the anthers, and appeared to be starting on the rest of the flower.


They didn’t seem to be much interested in the leaves, or in unopened flower buds


But once the flowers started to open, the beetles were right there.


So, anyway, here we are. One of the most widely-known lawn and garden pests has finally arrived in the area. And there was much sadness. In the previous post, I noted that there were possible ways to control them, but they left something to be desired. I suppose that at this point, we are stuck with them.

[1] By “wild roses”, I mean that they are minimally modified from the ancestral rose. They were planted on purpose, though, so they aren’t “wild” in the sense of spreading themselves about. Although, we do have some actually wild roses in the area: Rosa acicularis is found in the northern parts of North America, Asia, and Europe, encircling the North Pole, and there are patches of them scattered all around the area.

The main defense of wild roses against being eaten is their thorns:


These thorns are pretty effective against browsing mammals like deer, cattle, rabbits, and the like. They aren’t so effective against insects, though, and a lot of different kinds of insects love to eat rosebush leaves. The thorns are also pretty effective against gardeners. One wants to be cautious about where you plant wild roses, because once they get established they can take over an area and become difficult and painful to cut back or remove. As a result, there is at least one fantasy novel where wild roses are actually the villain of the book. The author is a gardener, and apparently has opinions about wild roses.

2 Responses
  1. Lyle R Laylin permalink
    August 31, 2021

    Just saw this article from Green Bay

  2. September 5, 2021

    Thanks for the link, Lyle. The way his numbers keep increasing down there in Green Bay, it sounds like they are still getting established and building up in numbers every year. Hopefully, they will do the same thing as most of the other invasive species, and build up to a peak level followed by a crash and becoming only moderately common.

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