How Rodents Make Their Mark


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Rodents have mastered the art of avoiding humans. During the day, they live behind walls, under floorboards, or in attics. When they do venture out, it is at nighttime, under the guise of darkness. Their inconspicuous behavior makes them difficult to track and catch, but they are traceable. Rodents drop clues - or marks - behind during their nocturnal scavenges. Using these marks can help guide you in your rodent capture.

Listed below are five ways rodents leave their mark.


Rodents leave droppings everywhere they travel, which can help uncover feeding areas and highly trafficked run lines.  Additionally, the size, shape and texture of droppings can help you determine which rodents are present, their diet, and if an infestation is active. 

Rats produce about 20-50 droppings per day, and mice produce around 40-100 per day. 


Rats and mice, just like humans, produce natural oils on their skin and hair. As they navigate their familiar routes, they deposit oils and dirt from their fur along walls and baseboards called sebum. Sebum marks look like grease marks and indicate a highly trafficked rodent runway. If the sebum smears when you touch it, you know that it is fresh.  Sebum can be spotted both indoors and outdoors near entryways, or along pipes, telephone wires, gutters, pipes, etc.  Bell’s T-Rex iQ rat snap traps, Powered by Bell Sensing Technologies, can be easily secured both vertically and horizontally to pipes and using zip ties.  These traps can be placed in hard to reach locations where rodents are traveling and checked via the Bell Sensing app, so you never need to check an empty trap again.

Burrows and Structural Holes

As discussed above, rodents like to stay hidden. As a result, they like to stay close to their food and water source.  Rats tend to live between 90-450 feet from their food source. On the other hand, mice can vary in how close they live to their food source, but a house mouse, for example, generally lives 10-30 feet from their food source.  Looking for burrows or structural holes can help you pinpoint a rodent’s food/water source.


Just as any other animal, rodents leave footprints that expose their run lines. To help expose a rodent’s run line, sprinkle cornstarch or talcum powder in areas where you suspect mouse activity. Check with the homeowner or facility before doing this.

Gnaw Marks

Rat teeth are constantly growing. If left unmanaged, their teeth could grow to be a foot long in just two years, leaving the rat to starve to death. To manage this incessance, rats must gnaw on anything and everything, including plastic, brick, copper, cement, and steel. Rodents are even estimated to be the cause of 20 percent of undetermined house fires throughout the United States, resulting in untold damages and deaths.  Doorways and other entryways are usual places to spot gnaw marks.


Before setting up any traps, use the marks listed above to help determine the best places to set your stations. Setting up traps along heavily trafficked areas can help you quickly and efficiently eliminate your client’s rodent issues.

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