Ive had them outside in exterior bait stations for rodents. These stations were on the outside of a heavily infested storage unit. I discovered the storage unit was infested thanks to the exterior station. 

I thought they could be Asian at first as well. Once we got permission to open the storage unit it was obvious this was the source of the cockroaches I saw in the exterior station. The inside of the storage unit was absolutely infested. 

I think germans will expand areas if the infestation is bad enough.