A true story.
The mosquitoes in Borneo were terrible. On bad days, the people of Borneo would be covered in mosquito bites.
(Leader — Ask, "And what do you suppose would happen?" Wait for someone to suggest that it would itch and people would scratch / make the bites bleed.)
That's right — those mosquito bites made them itch and scratch like mad. (Leader — Act out scratching and invite the children to do the same.)
The itching made them uncomfortable, but the real problem with the mosquitoes was that they carried a sickness called malaria. This meant that sometimes the people who got bitten by mosquitoes would get really sick or even die.
Scientists from an agency called the World Health Organization wanted to stop the people of Borneo from getting sick and dying from malaria. They decided to do something about those mosquitoes. They sprayed a chemical called DDT all around the villages of Borneo, because they knew that would kill the mosquitoes. It worked. The mosquitoes died and the people stopped catching malaria.
Everything seemed fine, but what the people didn't know at first was that the mosquitoes weren't the only insects that the DDT had killed. Some wasps died, too. These were parasitic wasps whose larvae ate caterpillars. Without the wasps there wasn't balance in the ecosystem. Because they were not there to eat the caterpillars' larvae, the caterpillar population began to grow and grow. More and more caterpillars were born and they were hungry. They ate and they ate and they ate.
The problem was, the people of Borneo lived in houses with thatched roofs made out of grasses. (Leader — Ask, "What do you suppose those caterpillars liked to eat?" When someone suggests the roofs, continue with the story.)
That's right, the caterpillars ate holes in the thatched roofs and soon the roofs began to fall in. The people of Borneo replaced the roofs, but ... (dramatic pause) there was an even bigger problem to deal with.
The wasps weren't the only insects that ate the DDT. Cockroaches and other insects did, too. So, the cockroaches and other insects began to get sick. And these insects were the food for Borneo's small lizards, the geckos. The more cockroaches and other insects the geckos ate, the more DDT got inside the geckos. The geckos started to die, too.
And the geckos of Borneo were eaten by cats. (Leader — Ask, "What do you suppose happened to the cats?" When someone suggests they died, continue the story.)
That's right, the cats began to die. But even worse ... (dramatic pause) the cats were important because they killed rats. When the cats died there wasn't balance in the ecosystem. There were not enough cats to kill the rats. So the rat population of Borneo grew and grew. The rats began to overpopulate. More and more rats were born.
The trouble with rats is that — just like mosquitoes — they often carry serious diseases which people can catch from them. Now the people of Borneo worried that they might have an outbreak of the plague or another illness that could kill lots of people. (Leader — Ask, "What do you suppose they did?" and take a few answers.)
The people of Borneo realized they needed more cats to bring back the balance in their ecosystem. Some were borrowed from neighboring villages but they still needed more. And that is why in 1959 members of the British Royal Air Force flew over Borneo in a helicopter and sent 20 cats in parachutes to the ground. Can you imagine that? Twenty cats in parachutes — all because nature got out of balance.
(Leader — Use the sound instrument to signify that the story has ended.)