We own a business that deals with all kinds of Nuisance Wildlife and the conflicts incurred with homeowners. This includes: squirrel trapping, raccoon trapping, beaver trapping, bat control and also Norway Rat & Roof Rat trapping. So we have definitely had a lot of experience with the issues concerning rat trapping & rat control.
I can tell you this - every customer that calls me acts as if they should be embarrassed that they have nasty dirty home. Rats do not seek out dirt or filth. They seek out food, shelter & water. You have to provide one of the three to have a rat situation.
When I talk to potential customers I could get rich from betting that either they have dogs or one of their neighbors have dogs. Then I ask if the feces is left on in the fenced yard. 99.5% of the time they say YES - then ask... "How did I know"? Then I have to go into this long dissertation about how the dog food these days has a base of CORN. Corn is non-digestible by the dogs so it is passed right through to their feces. Rats love corn!!!! Disgusting, YES but factual. If they or the neighbors cleaned up the feces right as it occurred then this problem with rats "Might" have been avoidable.
Regardless when you are hiring someone with a wildlife license it is imperative that the traps are checked daily. Here in the State of Georgia it is the law. Unless it is a Pest Control company that uses poison then they do not have to do daily trap checks.
The reason it is important is because it makes the most out of your trapping dollars. A trap with a rat in it will NOT catch another rat. It is occupied. Plus if the rats eventually associate the dead rats with this trap then they will learn to avoid it. It is called "trap smart".
We used all kinds of traps to catch rats. Lice cage traps, snap traps (different appearances) to mix it up. Regardless of the type or appearance of the trap, any trap left inside a building or home is concealed. Concealed by an outer box so the client does not see the rat - alive or snapped. No matter - no one wants to see any of the unpleasantries.
One thing that I want to discourage is the use of poisons (bait stations). More often than not we see inexperienced pest control companies, the only ones legally allowed to use poisons, set them improperly and causing more of a problem with dead animal removal than creating the solution. Terrible! When bait stations are set at improper locations the rats find it easier to run into your attic or walls to suffer from internal bleeding and possibly DIE inside you walls or attic. Yucky!
If you need help figuring out the right questions to ask when hiring someone to resolve your rat problem we developed a website dedicated to consumer awareness called rat control dot biz.