INSECTS AND DISEASES 415 



Fleas and bubonic plague. One of the most terrible 

 scourges recorded in history is that of bubonic plague or 

 " black death." This disease is caused by bacteria which 

 attack rats as well as human beings. It has been shown 

 that fleas are the means of carrying these bacteria from 

 rats to human beings. The flea sucks the blood of the rat 

 which contains thousands of bacteria ; later he may pierce the 

 skin of a human being, thus permitting the bacteria to enter 

 that cause the development of the disease. Not long ago 

 when the plague broke out in San Francisco, it was success- 

 fully controlled by waging a warfare on rats, which 

 indirectly the means of spreading the disease through fleas 

 that lived upon them. It was also found that ground squirrels 

 were subject to the disease and that fleas might carry the 

 disease from them as well as from rats. 



COMMUNITY PROJECT 4 



Purpose. To learn what the class can do to help control the 

 fly nuisance. 



Directions. I. The campaign may be started in the late 

 winter or early spring. Encourage the free use of fly traps. 

 Some members of the class may make fly traps to sell. Send 

 five cents in stamps to the International Harvester Company, 

 Harvester Building, Chicago, 111., for a fly trap pattern. This 

 gives detailed directions for making a fly trap in such a simple 

 way that any boy or girl can make one. 



2. For fifty cents there may be obtained from the same 

 company, a set of twelve stencils, three feet square, of the 

 house fly, giving drawings that may be reproduced on the 

 blackboard, on paper, or on cloth. Cloth charts could easily 

 be made by various members of the class. There might be 

 opportunities to use these charts by giving talks to some of the 

 rooms in the graded schools. Various members of the class 

 may be assigned to give a talk on the different charts, which 

 may be taken around to the rooms to be visited. The class 

 might prepare a whole evening's entertainment on the fly to 



