396 THE CANADIAN ENTOMOLOGIST. 



AN EARLY REFERENCE TO THE RELATION OF LNSECTS 



TO DISEASE. 



BY C GORDON HEWITT, DOMINION ENTOMOLOGIST, OTTAWA, ONT. 



In studying the evolution of ideas respecting the control of 

 insect pests, I came across an early reference to the relation of 

 insects to disease which is of interest more from an historical 

 point of view than as a serious contribution to the development 

 of the insect transmission theory of disease. Nevertheless, I 

 believe it is worthy of a place among our entomological documents, 

 and this is one of my reasons for calling attention to it. The other 

 reason is the relation it has to the ideas advanced by Nott (1848) 

 on the mosquito transmission of yellow fever by insects. Nott 

 has been generally accorded the credit of having formulated the 

 insect-transmission idea of yellow fever. Riley (1914)* however, 

 has recently pointed out that when Nott's argument is studied in 

 its entirety it does not support the conclusion usually claimed, 

 but that the term "insect" was used to denominate micro-organisms 

 in general. As the matter is fully discusssed by Riley in his paper, 

 I will not repeat his interesting statements here. In the quotations 

 which I am about to give I do not think that there is any ambiguity 

 about the meaning of the term "insect." 



In an old volume entitled "New Improvements of Planting., 

 and Gardening, both Philosophical and Practical," by Richard 

 Bradley, F.R.S., the fourth edition of which was published in 

 London in 1724 (this is the edition from which the extracts which 

 follow are made) the author quotes a letter from a "worthy Gentle- 

 man, Mr. Balle," which begins (page 254) : 



LIpon discoursing with, you some time since about Blights 

 upon Trees, you seem'd to be of the opinion that they were 

 the Effect of Insects brought in vast Armies by the Easterly 

 Winds and by lodging upon the Plants proper for their Nourish- 

 ment, they there produced that Distemper which is called a 

 Blight or Blast. 



You was then desirous of what Observations I had made 

 concerning Pestilential Distempers subject to Mankind, which 



''Journal ct Para'^itology, I, p. 37, 1914. 

 December, 1915 



