Cockroaches can find their way into an apartment or they can unknowingly be brought into an apartment by someone who lives there or a visitor. They only need water, a warm area and food to make their home in an apartment. They like dark areas in cupboards or small spaces and they only go out at night. If one is spotted, then there is a good chance that there are more roaches.
One option to get rid of the pest is to call a professional pest control company. Another option is to make a plan and control the situation. A professional company will use powerful pesticides which are not generally available to control the pest. The pesticides that are generally available need to make contact with the cockroaches so they may not be as effective.
They are very attracted to paper and cardboard items such as newspapers, bags and boxes. These items easily absorb the chemicals they use to mark locations that make points of a map that they follow to find their way around. Seal up any paper and cardboard or throw it out.
The apartment will have to be thoroughly cleaned and that includes the places where cleaning can generally be overlooked like under the microwave and the fridge. Taking away their food source will force them to move away and find somewhere else to live. Any patches of oil or grease must be completely removed because they particularly attract the roaches.
Having taken away their food source, the next step is to take away their water source. Make sure everywhere is dry and any drains are adequately covered. They need water but just a little condensation on a pipe or moisture in a plant pot is enough for them to drink and remain in the apartment.
Make sure that any holes or cracks in walls are sealed to help prevent any more from entering the apartment. Use sticky traps to capture those that are in the apartment and bait the traps with boric acid. Boric acid is available from local pharmacies and although it is not highly toxic to animals, it should not be located in an area where animals have access to. Boric acid is a powder and can also be lightly sprinkled in the warm damp areas under the sink where the cockroaches are likely to live.