When you observe that you have Des Moines rats on your roof, then you will need to immediately put in place steps to relocate or kill them. However, they are smart and tricky animals. This is not going to be easy. The steps you will have to take include:
Chances are that any opportunity they get; they could come into your Iowa house before going back up. The first thing you want to do is know how they get into your house and which part of your house. You should find or smell their droppings and urine in this area. If they have not started coming into the house, then you might need to check outdoors for the same sign as well as signs of holes they have gnawed. This knowledge will come in handy during the exclusion and reducing the rat population.
The next thing you will want to do is to ensure that your house is very neat. Pack food in containers with tight lids. Do not store things that attract rats like food in bags as they might eat the bag to access its contents. Remove cardboard and paper clusters that rats usually require for building their nest. Remove vegetation that is not needed around your house and also stores pet food properly.
You should block any hole or other avenues you observe the Des Moines rats have been using to access your home. This is considering they could force themselves into very tiny holes. All your windows and doors should fit and close tightly.
Set traps in those areas you have found their traces during the inspection. Iowa traps could be used to capture them for relocation without hurting them or to kill them. It is worthy of note that certain types of traps and methods for killing rats are illegal in some countries and cities.