Malaria once infected nine out of ten people in the part of north Borneo now known as Burnei Darussalam. in 1955, the World Health Organization (WHO) began spraying the insecticide dieldrin to kill the mamaria carrying mosquitoes. The programme was so success ful that the dreaded diseasse was lmost eliminated from the island. The strange things started to happen. The dieldren killed other insects, including flies and cockroaches, living in the houses. GREAT! People were delighted
Then the gechos, he small lizards which lived in the houses died after eating the dead insects. Then cats began dying after eating infected lizards. Without cats, the rats flourished and the villages were over run by a plague of rats. With the rats came the plague, carried by fleas on the rats. the situation was only brought under control when WHO parachuted healthy cats in to the country.
The roofs of the houses began to fall in. The Dieldren had killed wasps and other insects that fed on a caterpillar that either avoided or was not infected by the insecticide. With most of it predators eliminated, the caterpillar population grew rapidly. The caterpillar ate their favorite food, the leaves used to thatch the roofs of the houses. Eventually, the numbers of predatory insects recovered and the spraying program was a success story. But, it does not show the unpredictable results that can happen when humans interfere with nature.
When human interfere with nature 
