D. and I are at the edge of a slough in a marsh, at high tide. We are wading barefoot next to the bank when the water suddenly begins to recede, much faster than a normal ebbing tide. As the water gets lower we become aware of a storm drain on the opposite bank of the slough down which the water is rushing. The sinking water reveals a series of storm drains along the slough in the marsh. We are puzzled by this.
Then we become aware of high-pitched noises filling the air, like rhythmic, percussive squeaks. The noise gets louder as the water level gets lower. We cannot tell where it is coming from at first. Then D. realizes the sound is coming from the storm drains. He says, "Rats are coming! The water is driving them out!"
We are barefoot, with our pant legs rolled up. D. says, "The rats are going to chew us to pieces. There are thousands of them. We have to run!"
But then I see enormous beetles the size of my fist scurrying up from the drains, at first a few, then dozens, then scores, then hundreds, madly fleeing the onslaught of rats chasing them. The noise becomes deafening. I shout, "No, the chase instinct of the rats makes them lock onto the beetles as their prey. They will pass us by in pursuit of the beetles. Watch."
And sure enough, a horde of rats comes boiling out of the drain and flows in a concentrated wave past us, single-mindedly focused on the fleeing beetles to the exclusion of all else in their path. Within seconds they are gone, and with them the high-pitched noise. We are untouched, safe.