Question Sheet: Alien Invasions


Before reading:

  1. Is there a plant or animal in your area that is considered a nuisance but is not native to your part of the country? If so, what is it and how or why was it introduced? 
  2. To prevent the introduction of species that don’t belong in your area, what should inspectors check for in luggage when you come back from another country?

During reading:

  1. What percentage of invasive species cause problems? 
  2. How does New Zealand keep out potentially invasive species? 
  3. Name two things that Simberloff suggests might help solve the “hitchhiking critter” problem. 
  4. How has the introduction of the zebra mussel affected other species and the water where it lives? 
  5. What can tourists do to prevent the spread of non-native plants? 
  6. How are Simberloff and his colleagues attacking the ladybeetle problem in the United States?

After reading:

  1. Why are some non-native plants harmful and others not harmful? What makes a plant “invasive”? 
  2. How is the spread of a virus such as SARS similar to that of an invasive species? For information about severe acute respiratory syndrome (SARS), see for Disease Control and Prevention). What action did the United States take to keep this disease from spreading? Could similar measures be used to keep unwanted plants and animals from getting into a country? 
  3. Why is it important to maintain ecosystems and not have invasive species disrupting them? 
  4. Give four reasons why someone might deliberately bring a non-native plant or animal into this country. 
  5. How have people attempted to stop the invasion of the Africanized honeybee?

    You can learn more about the Africanized honeybee at (U.S. Department of Agriculture, Agricultural Research Service).


  1. What does invasive mean? Come up with three synonyms for “invasive.” 
  2. Find out what you can about how witchweed or gypsy moths came to the United

    States. See (U.S. Department of Agriculture) for information about witchweed and (U.S. Department of Agriculture, Forest Service) for information about gypsy moths. Invent a story that might explain how either one of these species was first introduced.


  1. Go to write a report describing which invasive plants or animals are in the area where you live. 
  2. Take a walk in a park or in the woods near where you live. Try to identify three plants that are not native to the area.


The United States spends about $130 billion dollars on identifying and battling invasive species. How do you think that money should be divided? What percentage should go to prevention? to education? to eradication? to other activities? Make a pie chart showing how you think the money should be divided. Include an explanation of your thinking. Suppose the total amount of money spent on the problem increases to $190 billion. Calculate how much money would be spent in each of the categories you defined.