PROBLEM 131 



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Conclusion. — 1. What diseases may be carried by flies? 



2. Where do they get the germs of these diseases ? 



3. How do they carry these diseases? 



Problem 130: What is the best way to catch and destroy 

 flies? (Homework.) 



Materials. — Flytrap, tin plate, carbolic acid, and insect powder. 



Method and Observations. — Make a flytrap according to the 

 plan shown ; bait it with stale fish or other food. Leave it for one 

 day, then plunge it into 

 boilingwater and count 

 the number of flies 

 which you caught. 



Heat a tin plate 

 containing strong car- 

 bolic acid so that the 

 fumes will fill a room 

 {e.g., the kitchen) con- 

 taining a number of 

 flies. What results ? 

 How does it compare 

 with your trap? 



Burn a few ounces 

 of insect powder in a pan in the same room on another day. 

 Compare your results with those above. 



Conclusion. — 1 . Which is the best method of those given for 

 destroying flies in your home? 



2. Knowing when and where flies breed, when would be the 

 best time to "swat the fly"? How would this method com- 

 pare with other ways of extermination studied? 



An easily made Flytrap. 



Problem 131 : To determine harm done hy insects. 



Materials. — Trips to museum, reference to texts, and various 

 bulletins of the Department of Agriculture. 



Observations. — Make out in the form of the following table a 

 report on the harm done by insects : 



