﻿138 <TAS. J. SIMPSON — ENTOMOLOGICAL 



Unfortunately, at present, it is not possible to detail with certainty, except in 

 a few special cases, which diseases are insect-borne and which are not. Further, 

 although certain insects have been proved to be the carriers of particular 

 diseases, it is far from certain that other allied species may not also be implicated. 

 For example, it is now known tbat Glossina palpalis and G. morsitans transmit 

 sleeping sickness from man to man, yet it is not possible to say whether only 

 these species of Glossina or only this genus may be capable of transmitting it. 

 Again, in the case of malaria, we know that this disease is transmitted by 

 Anopheline mosquitos, but of these there are many species, and, with the excep- 

 tion of a very few. no definite statement can be made as to which are or are not 

 innocuous. A third example is yellow fever. It is well known that Stegomyia 

 fasciata transmits this disease, but as to whether this is the only species capable 

 of such transmission no one will at present venture to say. Another disease, 

 unfortunately by no means uncommon in Southern Nigeria, is " Calabar swelling " 

 — but of the etiology of this malady practically nothing is known beyond the 

 fact that it is probably insect-borne. The same may be said of elephantiasis ; 

 and doubtless there are other maladies which, though at present not thus 

 associated, may eventually prove to be disseminated by insects. 



Enough has been said to emphasise the necessity for much experimental work, 

 and it is towards the stimulation of an interest in the entomological aspect of 

 such investigations that the efforts of this Committee are mainly directed. 



The first step in such an enquiry must naturally be a mapping out of the 

 various endemic centres of the different diseases, combined with a similar study 

 of the distribution of the various blood-sucking insects. Always remembering 

 that every blood-sucking arthropod is, so far as we know, a potential disease- 

 carrier, one must carefully record the distribution of each and every species. 

 When this has been done, it is more than probable that such maps, when super- 

 imposed, may give valuable clues as to the inter-relationship of certain diseases 

 with certain species of insects. This then is one of the first problems to 

 be solved. 



Our ignorance of such distribution is not due to any lack of interest or desire 

 on the part of the various officials, but in most cases to a lack of material for 

 collecting and preserving, or to the difficulty of obtaining identifications of un- 

 familiar species when collections have been made. Such collecting should always 

 involve the recording of observations, such as the nature of the habitat, e.g., whether 

 the species is found in the open, associated with bush, in houses, near water, etc., 

 the season of the year, the weather conditions, the time of the day, and so on. 

 An endeavour should also be made to ascertain the breeding-places, the different 

 immature stages, and the nature of the food supply, in fact, everything which is 

 essential or detrimental to the existence of the various species. This will form 

 the basis for prophylactic measures and will also help to indicate along what lines 

 insect-borne diseases may be expected to spread, and so be a means of preventing 

 any extension of the endemic areas. 



It is obviously useless for any one to carry on transmission experiments, to 

 dissect for parasites or such-like, unless he is perfectly certain of the species 

 with which he is dealing, so that the second step in this work is identification. 



