STEPS TO PROVE INSECT CAUSATION OF DISEASE 33 



reactions to heat and cold, moisture and dryness, disturbances, color, 

 light, odor ; its food, and the proper condition thereof ; its methods 

 of reproduction, and what food is necessary for reproduction ; if soil 

 should be provided, and what conditions it should be in ; if water should 

 be provided, and whether this water should be alkaline or acid, clear or 

 containing foreign matter, and in such case what type of foreign matter; 

 whether the water should be still or in motion, warm, moderate or cold. 



2. What type of breeding cage should be used? 



A breeding cage must be used which will most nearly enable the 

 experimenter to keep the insects under control and yet reproduce essen- 

 tial conditions for maintaining normal, healthy life of the insects and 

 normal reproduction. Much of this information is available in entomo- 

 logical literature. INIany insects probably involved in disease transmis- 

 sion have not been properly studied and breeding technique is yet to be 

 worked out. 



3. Water is necessary in some form in practically all insect breed- 

 ing. 



There are more failures to properly breed insects traceable to im- 

 proper humidity, or to the lack of moisture in the proper form for the 

 insects to drink. Much detailed observation may be necessary to obtain 

 this important information in the case of many insects. 



4. There is a combination of temperature and humidity most favor- 

 able for life, for each species, and differing from one species to another. 



5. The food of an insect must be in a particular condition in order to 

 obtain normal breeding. It may require a certain degree of immaturity, 

 ripeness, or fermentation. It may require a certain degree of desicca- 

 tion. 



Many other details must be attended to by each specialist involved 

 in the investigation, and we probably have yet to see a single disease 

 problem which has been completely rounded out and solved for the future 

 generations. 



