We moved into Iowa five years ago (though I had already worked here the previous year, while living across the river in Illinois). Apparently that’s about when the Japanese beetles moved here also. (I didn’t bring any with me, honest!)
Having been familiar with these insects from early childhood, I find it strange to realize that the pest is a newcomer to my neighbors here. We had rose bushes in our front yard, and I remember my mother picking Japanese beetles off the bushes. (That must have been when I was quite young; I don’t think she had any interest in purely ornamental plants later in my childhood.)
I don’t think I connected the beetles with their country of origin, despite their name. After all, I knew that French Fries and French toast weren’t from France, Spanish omelet wasn’t from Spain, and turkey certainly wasn’t from Turkey. Why would Japanese beetles be from Japan?
I don’t remember ever finding Japanese beetles while gardening at any of the houses I have lived in as an adult. But then, I haven’t done a whole lot of gardening as an adult. And what I have done hasn’t been all that successful. If there were Japanese beetles around, they probably went looking for plants that grew better than mine did.
As an adult I learned about the problem of invasive species. Often brought in by accident, these species have no (or few) natural predators (in their new habitat) to keep their numbers in check. In the case of Japanese beetles, the lack of grassy areas (i.e. food) in Japan also prevented them from being a serious pest. Here, most of the country is one big garden for them to enjoy.
The Mississippi River is a significant obstacle for them, however. They’ve become established in pretty much all the states east of the Mississippi, but west of the river they are found mostly in isolated pockets that can be more easily controlled.
As a child I read books (such as Tom Sawyer) that depicted the Mississippi as a mighty river, and when I finally crossed it the first time I was disappointed that it looked so ordinary. But against an insect that is a clumsy flier, the river is apparently doing a good job of halting its westward progress.