INSECTS AND BIRDS. 297 



which will corrode the body or stop the breathing 

 pores, as kerosene emulsion, whale-oil soap solution, or 

 strong tobacco decoction. As the bugs often congre- 

 gate on wild mustard in early spring it is practicable 

 to pick them off and destroy them by burning or sub- 

 merging in a can of kerosene. 



EXERCISE. Bring specimens of wormy apples, plums and peaches 

 to the classroom and see if the injuries are not due to one of the 

 insects mentioned in this text. 



Take the class out to an orchard and find San Jose scale and 

 other insects or insect injuries. 



If any farmer owns a spraying outfit, arrange to take the class to 

 his place, preferably when he is operating it. 



SECTION XLVII. HOUSE-FLIES AND MOSQUITOES. 



By DR. A. W. MORRILL, 

 Bureau of Entomology, U. S. Dept. of Agriculture. 



House Fly. Scientists are now using " typhoid fly " 

 as the common name of the house fly in order that 

 everyone may bear in mind the dangerous nature of 

 this insect as a carrier of typhoid fever germs. The 

 adult fly lays her eggs to the number of about one hun- 

 dred and twenty in manure and filth of various kinds. 

 Horse manure is the principal breeding place. The 

 young stages are completed in from ten to fourteen 

 days depending on the temperature. Scientists have 

 proven that flies carry on their feet and in their bodies 

 germs of typhoid fever, cholera, dysentery and other 

 diseases. While these disease germs are carried by 

 other means, flies are believed to be among the most 

 important agents in transmitting these diseases. The 

 typhoid fly can be controlled to a large extent in both 

 the city and the country by screening the storage places 

 for horse manure, and by the proper disposal of waste 

 material and human excrement when necessary. 



