The German cockroach is very good at setting up an ecological area in structures and is resistant in the face of many pest-control measures. To be successful, control procedures need to be detailed, sustained, and methodical; survival of just a few eggs is quite sufficient to regenerate a nearly eradicated pest population within a couple of generations, and recolonization from surrounding populations frequently is very quick, too.
German cockroaches like confined spaces, and they are small compared to other pest types, so they can hide within small gaps and crevices that are easy to miss, thus averting human beings and their extermination efforts.
A strain of German cockroaches has emerged that responds to glucose as distastefully bitter. They refuse to eat sweetened baits, which presents a barrier to their control, considered that those baits are an affordable and effective way of regulation.