No. G. DEPARTMENT OF AGRICULTURE. 32? 



KEPOKT OF IIENKY SKINNEK, M. 1)., ENTOAKJLOGI.ST, TO THE 

 STATE liOAKD OF AGIUCULTUKE. 



INSECTS AS FACTORS IN THE TRANSMISSION OF DISEASE. 



Hari'isbiii-g, Ta., January 23, IDOl, 



Probably the most important siibjoct at the present time is the 

 question of the distribution of disease by the agency of insects. 

 This is of vital importance, not only to scientists and medical men 

 who are laboring in the cause of humanity, but also to the agricul- 

 turist and horticulturisc, as these classes have many interests af- 

 fected thereby. These researches into the causation and transmis- 

 sion of disease and a knowledge thereof will aid the farmer in pre- 

 venting many maladies of his domestic animals, of his crops, and 

 also among the members of his own household. These subjects 

 also appeal to the farmer from a pecuniary standpoint, as the preven- 

 (ion of sickness and disease among domestic animals and in plants 

 means a great saving in money value, and if he can prevent disease 

 and the risk of death so far as he himself is concerned as well as 

 among those near and dear to him, it is not only a saving of time and 

 money but a prevention of sorrows that otherwise may be most dis- 

 tressing. 



Attention has been drawn to these important studies by the mor- 

 tality from disease among our troops during the late Spanish-Ameri- 

 can War, but the subject is not a new one. As far back as 1871, Dr. 

 Joseph Leidy, of the Academy of Natural Sciences of Philadelphia, 

 stated emphatically that in his ojjiuion the common house-fly was 

 responsible for the spread of hospital gangrene during our Civil 

 War. In 1882 Dr. A, F. A. King expressed his belief that mos- 

 quitoes were the agency by which malaria is conveyed to human 

 beings. In 1881, Dr. Ch. Finlay published a paper in which he took 

 the ground that the mosquito was the agent of transmission of that 

 dread disease of the tropics, yellow fever. Other observers abroad, 

 notably Dr. Patrick Manson in China, have shown that certain tropi- 

 cal diseases are distributed by mos(iuitoes. 



The growth of knowledge of the life history of the lower forms 

 of life has been slow and interesting and a brief reference to it mav 

 prove instructive. Anaximander, of Miletus, Greece (GIO B. C.) held 

 that animals were formed from moisture, and Aristotle (384 B. C.) 

 taught that every dry substance that becomes moist and every moist 



