The fast way for the German cockroach to infest a building where are multiple flats is from common waste pipes, plumbing and electric cables connecting the flats. The cockroach follow the pipes and access the kitchen and recycle areas where the people dump the food waste. Then if one flat has a cockroach infestation in a short period of time others get infested.
The German cockroach is hiding in many places like furniture, electronics and groceries aliments. It is an infestation in the building near your flat they easy can visit too.
German cockroach nest will be near a
Most likely places where cockroach-like to nest is behind fridges, cookers and other electric units in the kitchens and not only.
The best temperature for cockroach habitat is from 26′ C to 35’C