The first and most common sign of rodents, such as rats and mice in a home or business is noises at night.  Peak rodent breeding season starts around late September and ends around May in the Houston area.  Though they breed year round, it is during these cooler months that people experience the most intrusions.  This also coincides with the common Grey squirrel’s breeding season. 

The best way to distinguish between rats and squirrels in a home is when most of the activity is heard.  Squirrels are typically noisy at daybreak and can be heard leaving the attic and then again in the evening when it gets dark.  Rats are different as the are nocturnal making their noises at night. 

Rats also have an oil in their fur which contains a pheromone that we cannot smell or detect.  They lay down this smell along their trails which attracts other rodents and in some cases the predators that feed on them such as Texas rat snakes.   When rats have established a structure they tend to use one or two entry points and will generally travel the same pathways to get to the entry points.  Heavy travel of these pathways or entries causes a darkened stain to form and is a clear indication of a problem. 

Another indicator is droppings in the attic or clear trails in the insulation in the attic.  These trails will be most defined leading to the entries where the rats are entering the structure. Droppings will occur throughout attic, as rats and other rodents urinate and defect wherever they travel and don’t use a specific area.