Used the blue pellets in my garage once. They emptied the tray in one night. The next week we grabbed our bowling ball bags and headed to the alley for our weekly league night. It was quite comical when I pulled the bowling ball out and had blue pellets all over the floor.
I now use snap traps.
A very important part of storing a camper is getting every bit of food out of the camper. With no food or water they may visit but most likely will not set up camp. And it never hurts to set a trap right inside the door where it is easily checked.