PROBLKAI 131 



155 



Conclusion. — 1. What diseases may be carried l)y flies?. 



2. Where do they j;-et the germs of these diseases? 



3. How do they carry these (hseases? 



Problem i:u>: IJluU is the best way f<» cat eh and destrmj 

 flies? (Homework.) 



Materials. — Flytrap, tin plate, carbolic acid, and in.sect powder. 



Method and Observations. — Make a flytrap acconhn*!; to tlie 

 plan shown ; bait it with stale fish or other fo(xl. 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 nietliod com- 

 pare with other ways of extermination studied? 



An easily made Flytrap. 



Problem 131 : To deterviine 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 : 



