They spread disease: Many pests are identified to bring about many health problems. Rodents can transmit salmonellosis, hantavirus and also other severe disorders. Cockroaches can set off allergy indications and bronchial asthma. One of the BBC's most widely used presenters was 'assassinated on her doorstep in wide daylight' more than two decades back http://safepestcontrol.net.au/pest-control-for-food-processing-plants/