How to control cockroaches?

Boric acid is the cheapest and effective way to control cockroach population

Life cycle of roaches

The female can expel 6 to 14 egg capsules over 14 weeks. Each capsule contains up to 16 eggs. The eggs hatch between 5 to 7 weeks. They reach adulthood in 15 months, and live another 15 months as adult. Reproduction also depends on temperature. Lower the temperature, longer is the reproductive cycle.

Nesting and food

Roaches nest in warm moist and dark areas and forage for food at night. After you turn out the lights in the kitchen, they wait about four hours to come out for food. When they are out, if you turn the lights on, they run back to their nesting place.
Roaches eat almost any fresh or decaying organic food. They can extract nutrition from starches binding the books, or used in paste to put up wallpaper.
Oh yes! roaches love stale bread, pop and beer.
An adult can live without food for at least 2 to 3 months, and one month without water.

Health impacts

Roaches can carry serious disease organisms such as: salmonella, dysentery, gastroenteritis. The roaches shed their skin. The discarded dry skin can cause asthma in children and elderly.

Prevention

1. During summer, the roaches travel from building to building as well as apartment to apartment within the same building. Seal the cracks in foundation, mend seals and caulk around the windows and doors.
2. Inspect the grain and vegetable sacks being brought from the store, specially the sacks of potatoes. Destroy roaches found on the sacks.
3. Clean cooking range top, sink, counter tops. Wash dishes. Don't leave any food scraps including partly consumed beverages in open. Take out garbage to outdoors and transfer to roach-proof receptacles.
4. If you have pets, remove the the food and water for the night.

Sprays

The most common house hold spray consists of Pyrethrin. This attacks the nervous system and kills the roaches. The Pyrethrin is also effective against many flying insects. It is a poison and must be used carefully.

Boric acid

Boric acid is a white powder derived from Boron. Boric acid powder is the most common and effective manner to kill roaches. The boric acid gets absorbed in the body as the roaches are crawling around. The tiny particles of dry boric acid get lodged in the joints making them lose water and die of dehydration.
Boric acid powder should be dusted near nesting area around the walls in a very thin layer barely noticeable to the eyes. Thick layer will be avoided by the cockroaches as an obstacle. Don't let the Boric acid get wet.

It will take about one week before a decline in the roach population may be noted.

Boric acid can cause respiratory problems if inhaled.

Cockroach Baits

Cockroach baits contain a slow-acting insecticide. The cockroaches crawl into bait traps eat and die. Some carry the bait back to nesting area where it kills other roaches. The poison is also expelled in the sputum and feces which is ingested by other roaches killing them.
The bait trays should be put under sinks, refrigerators, dishwashers and stoves, next to garbage containers and inside the cabinets and storage areas. The trays must be flush  into corners or up against edges or walls, so they are in the common pathways traveled by the roaches. A tray placed in open in the middle of the kitchen will not accomplish anything.

It will take about one week before a decline in the roach population may be noted.

Normally, I do not mention any products by name. I will make an exception here. Three  most effective baits are: Combat(R), Raid Max(R) or Roach Ender(R), and Roach Bait (Black Flag).

Biological Control

Biological control is not used in residential houses. In nature, organisms such as toads, beetles, mites and wasps attack roaches. The ladybugs control the roach population in many rural homes. The parasitic wasps are successfully used in non-residential commercial buildings, they are harmless to humans and feed on roach eggs.