Why you have Cockroaches:
Roaches enter buildings in search of food and water or they may be transported in packaging or garments. Once in they multiply quickly, so you have to be very careful not to offer food and water. You should also be sure to avoid allowing the roaches to find a point of entry into your home. Keeping your home clean, free of standing water, food, and even crumbs will help prevent the welcoming of these dirty insects.
While cockroaches do not bite and are not poisonous, they can pick up disease-causing organisms either in their guts or simply on their body parts and legs. Subsequently the germs can be deposited on kitchen surface areas, utensils, and food items. Cockroaches have been known pick up Salmonella bacteria on their legs and later deposit them on foods, thus causing food poisoning. House dust containing cockroach feces and body parts can trigger allergic reactions and asthma in certain individuals. They are frequently found in restaurants, grocery stores, and bakeries and are also associated with commercial kitchens, boiler rooms, sewers, and steam tunnels. Cockroaches leave chemical trails in their feces as well as emitting airborne pheromones for swarming and mating. Other cockroaches will follow these trails to discover sources of food and water, and also discover where other cockroaches are hiding.