South-Western College Publishing - Economics  
Bats are Worth More to Us Than Just Fighting Crime
Topic Economic Analysis
Key Words Imports, Exports, and Trade Surplus
Full Article

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Reference ID: A156734027

News Story Every spring, the skies of the Southwestern United States teem with free-tailed bats, ready to feast on cotton bollworms. Flying from Latin America northward, these mammals provide a valuable service to cotton farmers.

By assuming that each bat eats about 10 bollworms a night in mid-June (which is determined by looking at the stomach contents of the bats), each bat saves about $0.02 worth of cotton each night in June. And multiply that by millions of bats over the course of the spring and early summer, and you have a lot of money. It's a natural pesticide; no one has to pay for it. And farmers elsewhere are helped. Free-tailed bats help pecan growers in Georgia, sugarcane growers in Hawaii, and vineyard owners in California.

Some people are paying to promote it. Cotton farmers have taken to constructing bat houses (complete with belfries!) to induce bats to nest there. And some are trying to prevent it from happening. Fear of rabies and vampire bats lead people to slaughter bats both here and in Mexico. And that destruction along the food chain can lead to destruction of cotton and other things that we would never have considered before trying to kill Dracula.

Discussion Questions:
1. What does fear of rabies and vampire bats do to the price of cotton?
2. According to the article, many cotton farmers are beginning to construct bat roosts to entice bats to come to their farms. What does that say about the marginal benefits and marginal costs about such actions?
3. If we were to calculate the total economic benefit of having bats in the US, what would we have to do?
Multiple Choice/True False Questions:
1. What does the use of bats in cotton production do to the price of cotton?

  1. Keeps it low because the amount of cotton will remain high.
  2. Keeps it high because the amount of cotton will remain high.
  3. Keeps it low because the amount of cotton will remain low.
  4. Keeps it low because the amount of cotton will remain low.
2. What does the use of bats do to the costs associated with cotton farming?

  1. Raises them.
  2. Lowers them.
  3. Keeps them the same.
  4. Unclear because we don't know how much the bats cost.
3. If we assume that there are 4 million bats in the Southwestern US from 1 May to 15 June (46 days), and each one saves about $0.02 of cotton per day by eating the bollworms, how much total cotton has been saved in this period?
  1. $80,000.
  2. $1,200,000.
  3. $2,400,000.
  4. $3,680,000.
Source "Fear Vandals, not Vampires." The Economist, January 4, 2007.
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