Beetle Traps and Jail Cells

Our neighbor’s Japanese beetle trap is brimming with dead and dying beetles. Maybe I should get one, too. It’s intuitively obvious: More trapped beetles mean a healthier garden, right?

Not so fast. The scent in the trap lures beetles from more than half a mile away. Some wind up in the trap. Others, attracted by the scent, nibble the roses. Unless the trap is placed exactly so and cleaned out frequently, more beetles infest the garden than ever.

I thought of the beetle trap on hearing a recent agency chief praised for overseeing a record number of arrests. I lack the expertise or data to know, in his case, whether more arrests improved or worsened public safety. "Intuitively obvious" doesn’t mean accurate. This I do know: To assess the well-being of a garden or a nation, how many beetles have been trapped—or individuals arrested, or guilty verdicts rendered, or jail cells filled—is the wrong question to ask.