Where do cockroaches in the apartment come from?
They most often enter from service shafts, from neighbors, through wall gaps or with deliveries (cardboard boxes, appliances). In apartment blocks the problem usually affects several flats at once.
They are attracted by easy access to water and food scraps: sink, bin, pet food, leaky containers.
What works best?
The most effective methods are professional gels and baits, spraying in nesting areas and sealing entry points (cracks, vents). The key is to hit nests and routes of movement.
Aerosol “bombs” often give only short‑term results and disperse the insects. If the problem is in the building shaft, without action in several apartments it may keep returning.
How to prevent them from coming back?
Eliminate water sources (leaking traps), store food in closed containers, clean up crumbs and grease, and empty the bin regularly.
Seal gaps, install meshes/grilles and monitor critical spots: under the sink, behind the fridge, near the dishwasher.