Regarding cockroaches, were able to survive for months without feeding, but it is necessary because the water, because this choose to live in a damp place. So do not under any circumstances be allowed water in the kitchen sink and in the bathroom. Great care to not leave food residues without protective cover. Cockroaches are attracted to areas that have been contaminated with feces from other cockroaches, and so dark and wet spots, choosing cockroaches must be cleaned thoroughly. Since mixed powdered sugar with baking soda the same quantities, and left as a bait in areas frequented by cockroaches, then it will die because the soda is poisonous to their body. Another method to died cockroaches are sprayed with soapy water or alcohol lamp. Either quickly or more then it will die when these substances would act in their organization. Garlic, naphthalene, bay leaves, and slices of cucumber, a positive impact because cockroaches hate the smell.
As for the flies, they are treated even more difficult because there is no direct 'medicine'. Surely flies can be effectively addressed by a flapper with some traps of glue. Apart from these, the flies can be addressed with Greek coffee. Sufficient for a small cup of coffee to have some coffee while inside a burning brush to burn slightly. The smell of the brush in combination with the coffee repel flies and mosquitoes and wasps! Even a bunch of sage placed on doors and windows will repel flies and many other insects. Finally stores there are many electronic devices that generate ultrasonic repelling except flies, cockroaches, mice, moths, and fleas.