32 SANITARY ENTOMOLOGY 



8. Can the organism be demonstrated in the mouth parts of the 

 insect at the time of feeding? 



9. Can the organism be found in any of the excretions of the 

 insect ? 



10. How long is it before the organism reaches the mouth or the 

 rectum? 



11. What is the earliest date at which it can be found in the 

 feces ? 



12. What is the earliest date at which infectivity of the host can 

 be obtained by the sucking of the blood? 



13. What is the earliest date at which infectivity can be obtained 

 by scratching in of the feces or portions of the insect? 



14. Can infection be obtained by either natural or artificial inocula- 

 tion without demonstration of the organism? 



15. Is the infective organism,, contagium or virus filterable? 



16. Can the virus or organism be transmitted hereditarily by the 

 insect ? 



17. At what stage of development in the second generation does 

 hereditary transmission become possible? 



18. Can the organism be taken up by the immature stages, feeding 

 in infected excreta? 



19. Can the organism be taken up by immature stages of an inverte- 

 brate feeding on the host? 



20. How long can the immature forms of the invertebrate, infected 

 by whatsoever manner, retain the organism in their system? 



21. Does the organism stay in the insect during metamorphosis? 



22. Does the organism undergo any changes preceding or following 

 metamorphosis of its invertebrate host? 



23. At what stage in the metaiporphosis does the insect begin to be 

 infective after taking up such organisms? 



24. How long can the insect remain infected and infective? 



IX. HOW SHOULD EXPERIMENTAL INSECTS BE HANDLED? 



A large proportion of the failures in studies of insect transmission in 

 the past have arisen from improper handling of the insects. The breeding 

 and handling of the insects is an art in itself, just as is the culturing of 

 bacteria or protozoa. In fact, there are more diverse requirements 

 for handling insects of different species than can be found elsewhere in the 

 animal kingdom. 



1. What must be known about the insect before beginning trans- 

 mission experiments? 



The normal conditions of life of the insect must be ascertained: — its 



