The German cockroach is very good at setting up an ecological area in buildings and is durable in the face of lots of pest-control treatments. To be successful, control procedures should be extensive, continual, and methodical; survival of just a few eggs is quite adequate to regenerate a virtually exterminated pest population within a few generations, and recolonization from surrounding populations frequently is extremely fast, too.
German cockroaches prefer confined spaces, and they are small compared to other pest species, so they can hide within small gaps and crevices that are easy to miss, therefore evading people and their extermination efforts.
A strain of German cockroaches has emerged that responds to glucose as distastefully bitter. They refuse to consume sweetened baits, which creates a challenge to their control, given that those baits are an economical and effective means of regulation.