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, ISO: What is the best way to batch 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 

 boiling water 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 by 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 : 



