Pesticides What are pesticides? A “ pest ” is any living thing that harms crop growth, carries disease or causes damage. Some methods of pest control are natural, but other methods use chemicals called pesticides. Fly spray, rat poison and similar things you may use in everyday life are all pesticides. Why do we need pesticides? Farmers use pesticides to protect crops from insects, diseases and weeds while they are growing. They also prevent rats and mice, flies and other insects from contaminating foods when they are stored. Pesticides help us control ants and cockroaches in our homes and destory mites and ticks. Pesticides in wood and wool make our furniture and clothes last longer. Why are people concerned about the use of pesticides? Pesticides can be useful, but they can also harm people, wildlife and the environment. This is why there are strict controls over their sale and use. Many people object to their use because pesticides can contaminate our drinking water and cause health problems. Some of the most commonly used pesticides are toxic to animals and humans and large amounts make us ill. They can give us headaches and stomach ache, damage oru skin, hair and nails, and lead to weight loss. Experts believe that some of them can even cause cancer. 1. Pesticides ar chemicals.