When settlers first went to Australia they took a large number of rabbits with them. These animals were kept for food, as well as for their fur. However, it was not long before some rabbits escaped and, without any natural enemies, they spread all over the country. Rabbits breed rapidly and the large numbers became a serious problem. The solution was to introduce a rabbit disease, myxomatosis, from rabbit populations in other parts of the world. Within a short time the numbers had decreased to manageable levels.

There was a similar problem with the introduction of Prickly Pears into Australia which were brought to decorate gardens. Soon the plants "escaped" and without natural enemies, overran much of the country. To control the Prickly Pears a caterpillar that feeds off the plant was introduced and this successfully brought the numbers down. Scientists had to be careful, however, to choose a caterpillar that would not be harmful to plants and flowers native to Australia.

Now answer these questions:

1. Why did settlers take rabbits to Australia?
2. What might have stopped the spread of rabbits across Australia?
3. Why was myxomatosis introduced?
4. How large is the rabbit population today?
5. What is a natural enemy?
6. Describe the similar problem to the Australian rabbits.
7. How do you think the Prickly Pears "escaped" from the gardens?
8. How was the Prickly Pear problem brought under control?
9. What was the danger in introducing the caterpillar?
10. Explain the hazards of bringing new plants or animals to a country.