3. Droppings
As I said before, cockroaches leave droppings behind wherever they are. The shape and size of droppings vary between species. Some of them leave behind a small brown stain. German roaches, for instance, leave behind coffee-ground-like droppings that can also resemble pepper. The larger American cockroach species, on the other hand, leaves behind specks that are closer to a grain of rice.
The most common areas to look for droppings are cabinets, floor corners, under the stove, and under the fridge. In other words, any dark place. When you find this type of trace, the first thing you should do is clean it right away because it can spread bacteria and increase your chances of getting sick. The second thing is pretty obvious: hire a professional cockroach pest control team.