Action Outdoors
Educational Resources for Teachers and Schools

Biomagnification and DDT
Classroom Activity

"Operation Cat Drop"

Teacher Biomagnification and DDT poisoning is a classic example of how interference in natural ecosystems can cause unexpected results. Relay to your class the story behind "Operation Cat Drop" and discuss the problems and solutions. Then look at other ways we effect ecosystems. (i.e.: oil spills, dumping trash, etc.).

Students love this story and will remember it and the concepts for years.

"Operation Cat Drop"

In the early 1950s, the Dayak people in Borneo suffered from malaria. The World Health Organization had a solution: they sprayed large amounts of DDT to kill the mosquitoes which carried the malaria. The mosquitoes died the malaria declined; so far, so good. But there were side-effects. Among the first was that the roofs of people's houses began to fall down on their heads. It seemed that the DDT was also killing a parasitic wasp which had previously controlled thatch-eating caterpillars. Worse, the DDT-poisoned insects were eaten by geckoes, which were eaten by cats. The cats started to die, the rats flourished, and the people were threatened by outbreaks of sylvatic plague and typhus. To cope with these problems, which it had itself created, the World Health Organization was obliged to parachute live cats into Borneo. (McShaffrey, 1999)