If you see cockroaches more often in house they contaminate food and cause illness and if you find termites they affect your household furniture wooden structure and construction. Like wise, for bird, ant, bedbug, rat ,mouse, etc. also harm some other thing. Pest control should be done at least once in 6 months which is enough but it also depends on pests as monthly treatment maybe required if there is no control to pest. Also, there are various types of home pest control methods like electronic, biological, organic, chemical and hornet nest removal