"Currently the Japanese beetle is the most widespread pest of turfgrass and costs the turf and ornamental industry approximately $450 million each year in management alone " Anecdotal evidence of increased sales of pesticides and beetle traps indicates that these nasties are proliferating. Anything green West of the Mississsipi is fair game for them (see range map graphic after the fold). And of course we have obligatory "consistent with climate change" finding: "Japanese beetles, a voracious eater of turf and trees, live longer under higher levels of carbon dioxide" (found in subscription only research paper but oft cited in press coverage).
More than increased levels of C02 are involved however. Where this writer lives, the species of shrubs and trees preferred by the Japanese Beetle have been completely devastated by swarms for two years running. Thirty-foot specimens of birch were fully denuded by the start of July. Apples, barely producing fruit, look as if a hurricane stripped the foliage.
Like to grow grapes, peaches, apples, or tea roses? Forget it. They're all pillaged and gone, with many specimens likely to die over the next winters from excessive beetle grazing.
With beetle population densities on the increase, the widely sold Japanese Beetle traps (pictured is a bait box for one brand) are worthless. Pesticide spraying can't keep up even if you wanted to have that much poison in the air. We're not even sure that milky spore disease treatments would help, given how a puff of wind can transport zillions of them from the one neighbor who does not treat.
With suburban land owners universally bent upon providing the perfect habitat and plenty of food for Japanese Beetles, and with few predators interested in them, all it takes is a couple of "extraordinarily" warm winters to encourage high rates of larval survival, making a "beetle boom" certain. These guys are unstoppable unless winter frost depth returns to something closer to what you'd expect in the 1950's.
Hard winters are not going happen very often with the climate warming up. It's predetermined that the arboreal face of suburbia will change in the face of their merciless chewing. The sounds of chain saws and stump grinders serve as one more bellwether of climate change.