> In the 1950s in the Midwest there had already been farmland all over for 50+ years. Same with Ireland (for hundreds). The insect populations have only noticeably declined in the last few decades. Unfortunately, we don’t have enough historical data to confirm what it is exactly. Even in the 1970s you’d have solid layers of bugs on windshields driving between cornfields. Now, nothing.

This assumes that farming methods have remained identical since the 1950s or 70s, but they haven't. I don't know if the parent poster is correct, but I don't think is a good argument unless you also account for changes in agricultural practices in the last 50+ years.