ENTOMOLOGICAL NEWS. [April, '13 



Some Sources of Laboratory Material for Work on 

 the Relation of Insects to Disease.* 



By WILLIAM A. RILEY, Cornell University , Ithaca, New York. 



The great discoveries during the past twelve or fifteen years 

 regarding the relation of insects to disease have made it im- 

 perative that departments of entomology be prepared to give 

 at least elementary instruction along this line. When one 

 undertakes to outline some such work the question of securing 

 material immediately arises. 



There is comparatively little difficulty in obtaining various 

 parasitic mites and ticks, lice and bugs, house-flies, mosquitoes, 

 and fleas, in their different stages, and it is important that such 

 should be available for laboratory study. Very much zest and 

 value can be added to the work if there be available also some 

 of the parasitic protozoa and worms which are transferred by 

 arthropods, but there is usually the feeling that these, with the 

 exception of the human malarial parasite, are tropical forms 

 and beyond reach. When one investigates conditions, how- 

 ever, he finds that even in our Northern States there is a sur- 

 prising variety of forms which may be utilized to great ad- 

 vantage. It is for the purpose of calling attention to some of 

 these and getting the experience of others that I have chosen 

 this topic. 



We do not have the fly-borne germ of the nagana or of the 

 dread sleeping sickness, but we do have the first discovered 

 trypanosome of warm-blooded animals the Trypanosoma 

 lezvisi of the brown rat. This parasite is transferred by the rat 

 flea and louse. For practical purposes it is more valuable for 

 laboratory study than any other of the genus, and certainly 

 shows all the detail that would be desired. It is practically 

 cosmopolitan in distribution and has been found in this country 

 at least in Detroit, Lincoln, Philadelphia, Ann Arbor, Madi- 

 son, San Francisco, Urbana, Baltimore and Ithaca. It may be 

 transferred from rat to rat white or brown by the crudest 

 of injections and thus kept for laboratory study. If one has 



*Contribution from the Entomological Laboratory, Cornell Univer- 

 sity. 



