DESTRUCTIVE ANIMALS 545 



devoured. Hundred of thousands of dollars' damage is done 

 annually to oysters in Connecticut alone by the ravages of star- 

 fish. During the breeding season of clams and oysters, the boats 

 dredge up tons of starfish which are thrown on shore to die or to 

 be used as fertilizer. 



The liver fluke kills thousands of sheep every year. Tapeworms 

 in cattle and trichina in hogs spoil much valuable food. Round- 

 worms enter the bodies of food fish as parasites and kill large 

 numbers annually. Boring mollusks, such as the whelk, destroy 

 multitudes of other mollusks as food. Parasitic insects abound 

 which kill useful insects, some of which, like the honeybee, pro- 

 duce food. We can hardly estimate the harm done by one-celled 

 parasites and their carriers, the ticks, mites, etc., for they are 

 enormously destructive to cattle. 



Fish feed upon crustaceans and mollusks. The dogfish, shark, 

 and other elasmobranchs destroy many lobsters, crabs, and 

 other crustaceans, while many bottom-feeding fish eat mollusks. 

 Fish are cannibals also, eating the eggs and young of their own 

 kind. Salmon eggs are a favorite food of the western trout. 

 Birds eat many fish and much other food. Large numbers of fish 

 are killed by minks, otters, seals, and other fishing mammals. 

 At one time it was estimated that an annual loss of fish equal to 

 $20,000,000 was caused by carnivorous animals, such as wolves, 

 coyotes, and others. But this amount is rapidly decreasing. 



Practical Exercise 24. Make a table to show the kinds of damage done by 

 the animals common to your locality. Can you estimate the loss in dollars 

 and cents? Get information from local farmers, cattle and sheep raisers, 

 and your Chamber of Commerce. 



Rats as pests. David E. Lantz of the Bureau of Biological 

 Survey is authority for the statement that the rat is the most 

 destructive mammal in the world. He estimated the actual 

 money loss from destruction of property by rats each year in this 

 country to be over $200,000,000. Rats destroy the timber in 

 houses, they cause fires by gnawing matches, they destroy great 

 quantities of standing grain and stored food, they kill myriads of 

 young chickens and other poultry and untold numbers of young 

 birds. Worst of all, they spread diseases, especially bubonic 



