While you are placing your pet under medicated flea control in Derry, it is also important that you help them by getting rid of these pests in your home. You may hire a professional pest control company for $100 to $300 to spray your home with Derry flea control treatments. Some companies charge around $125 to $140 for a single treatment inside and outside of your house. This service has a 90 day warranty. In severe cases of infestation, a follow up treatment is needed which can cost you an additional $90 to $100.