Run! Or At Least Skitter...

The cockroaches are assembling! Oh, wait - they've probably always been utilizing the wisdom of the crowd - it's only that dense humans have just discovered it:

Apparently, cockroaches make group decisions. Some Belgian scientists took 50 of the humble Blattella germanica and put them in a tank that had three little cockroach huts, each of which could hold 40 cockroaches. The roaches divided themselves up perfectly into two groups of 25 each, and left the third hut vacant. When the researchers repeated the experiment so that it had three huts with a capacity of 50 each, all the cockroaches assembled in a single hut, and left the other two vacant.

(More at Collision Detection.)