Some things you just can’t get out of your head.

In yesterday’s Writer’s Almanac, Garrison Keillor discussed the “largest recorded swarm of locusts” in American history, which took place on July 20, 1875. Locusts have been a plague at least since the time of Moses whose god set them on Egypt where “they covered all the ground until it was black. They devoured … everything growing in the fields and the fruit on the trees [until] nothing green remained on tree or plant in all the land of Egypt.”

Still, it’s hard to imagine that the Bible-reading farmers of the Great Plains were prepared for what came out of the sky: a swarm 1,800 miles long and 110 miles wide, as 10 billion insects descended as one giant organism and devoured everything in their path – every stalk of grain, the bark off trees, laundry hanging out to dry, tool handles and fence posts. They even ate the clothes right off farmers who tried to scare them away.

And then, when they had eaten everything, they disappeared as suddenly as they had arrived. No Rocky Mountain locust has been found alive since 1902.

Nobody has missed them very much, other than some entomologists for whom the fate of the locust remains a mystery to be solved.

For me, the mystery is how quickly the world we take for granted can be upended. I’m not suggesting that Washington is filled with locusts, but as I read the newspaper each morning, I realize that we can no longer assume the continuity of government on which we have, for better or for worse, up to now, relied.