Australia has about forty kinds of bats. They are the world's greatest killers of mosquitoes.People are trying to learn more about their life. They catch them and put small pieces of metal on their legs.On the metal pieces people write the date and place. Then they wait for these bats in other parts of Australia. Some bats travel over one hundred and fifty kilometers from the places where people catch them. How do you catch them? Easily - just take them from the roofs of caves where they are sleeping.