ZOOLOGY FOR MEDICAL STUDENTS CHAP. 



MOSQUITO CONTROL 



Malaria one of the most debilitating and widely spread of all 

 .md Yellow Fever one of the most dangerous, not to mention 

 lesser diseases, being spread entirely by the bites of mosquitos it follows 

 keeping down the numbers of these insects to the minimum, 

 in re- ions where natural conditions favour their existence, is an insistent 

 need. Its successful accomplishment may indeed be an essential condi- 

 tion to the continued existence of a white community in a particular 

 locality. 



It is in warm climates where mosquitos carry on their life-history 

 throughout the year that their control is especially necessary. In regions 

 preading tropical swamps it is of course out of the question to 

 think of exterminating mosquitos entirely, but even in such places much 

 may he done to diminish their numbers within actual human settle- 

 ments owing to the fact that normally mosquitos do not travel any great 

 distance. 



What renders the problem of mosquito control a practical one is the 

 fact that the earlier and normally much longer portion of the life-history 

 is passed in the form of a larva (Fig. 107,, I) or pupa (Fig. 107, II,) which 

 lives in water but has to breathe air by means of a pair of stigmata, 

 situated in the pupa of Anopheles and in the larva and pupa of Culex at 

 the end of projections from the body. The line of action indicated there- 

 is to take measures (i) to ensure, if possible, that bodies of water 

 suitable for the larvae and pupae shall not exist in the immediate 

 'ibourhood of human habitations, and (2) should such be in existence 

 M'lcr them uninhabitable by the mosquito larvae and pupae. The 

 r object may be attained most easily by covering the surface of the 

 r with a thin film of oil which blocks up the stigmata and renders 

 i' impossible for the young mosquito to breathe. The oil 1 may be 

 i to the surface of pools two or three times a week, or allowed 

 to drip from a tin or drum with a small hole plugged with cotton waste. 

 lerely temporary in its effects and in the case of permanent 

 ore definitive measures are required. All unnecessary 

 wrater which may afford suitable breeding grounds for 



; oil. Its efficiency is said to be much increased by the addition 



rrd in the following way. Carbolic Acid (150 gallons) is 



ty Ix'ilm- point and J<esin (150-200 Ibs.) stirred in till dissolved. 



(30 Ibs. in o gals, water) is then added and the whole 



lll<)Ut '' If a little of the larvacide is added to a little 



' '-mulsify : if it does not do so it should be heated further until 



it does (Jacobs). 





