472 SANITARY ENTOMOLOGY 



SUMMARY 



Throughout this course of lectures my main object has been to show 

 the diverse manner in which insects may cause pathological conditions or 

 may transmit pathogenic organisms. Unquestionably the majority of 

 species which carry disease organisms have not yet been recorded in this 

 role. In the past we have attempted to minimize the possible role of the 

 insect as a carrier of disease. In the future it would be wise to take the 

 stand that insect transmission of a disease should be one of the first 

 methods of transmission investigated and that the investigation should 

 be carried out on logical lines suggested by the habits of the insects 

 concerned. It is to be regretted that a large part of the study of insect 

 transmission of disease has been aimed at proving or denying transmis- 

 sion by means of the bite of the insect. We have seen from the evidence 

 presented that a large proportion of the cases of insect transmission are 

 not by the bite but rather through the feces of the insect. We may 

 therefore consider that many of the conclusions that insects are not in- 

 volved in the transmission of certain diseases are unwarranted and that 

 the cases should be reopened and studied more scientifically. 



Any insect which visits excreta or which visits food or the person of 

 man or animals is to be considered a suspicious object in a disease 

 transmission inquiry. Naturally we will look to the blood-suckers as 

 the first means of transmitting disease of which the organism is found in 

 the blood, but when the diseases are of the intestinal or genital organs, 

 we are more apt to find that the disease is carried by insects which become 

 contaminated by contact with infected excretions. Another unexplored 

 field of study is the determination of toxins in foods, produced by con- 

 tamination of insects feeding therein. 



If through this series of lectures we have succeeded in interesting a 

 few investigators to look into the subject of transmission of certain 

 diseases more thoroughly, we shall feel that we have been successful in our 

 efforts. 



