I spent about fifteen years as a disaster volunteer with the Red Cross. Most of the events were fires here in Boston in some of the less affluent areas. In entering some of these burnt out buildings within minutes after the fire was extinguished, I would see what looked like a charred wall moving - however it was merely thousands of cockroaches that were parading over the still very hot surface. They were still milling about three hours later when everything was down to the 5 degrees outside temperature of February. They will survive almost anything.