You will know if you are dealing with a Rat Patrol infestation by examining the droppings they leave behind. Look for these small red marks most often in alleyways, on dumpsters, or the back of road signs. The markings are best encountered in undisturbed, out of the way places, where they are only likely to be discovered by those looking for them.

To help you recognize what to look for, we have reproduced a handy chart for your use.