ZOOLOGY FOR MEDICAL STUDENTS CHAP. 



ust the bites of infective mosquitos. In regions where 



re abundant it is quite impossible when leading an ordinary 



out-oi-d.>or lite to avoid altogether being bitten. But it should be 



rememU-ivd that only a small proportion of mosquitos are infective and 



consequently any reduction in the number of bites means a reduction in 



of infection. The hours of sleep should be passed in the 



u efficient mosquito net,, properly used, and for persons on 



ni-ht duty in the midst of swamps it is worth while to smear the exposed 



i' the skin with some oil repellent to mosquitos and other biting 



insects 1 although such mixtures are themselves apt to cause much 



irritation to persons with delicate skins. In the case of regions where 



malaria is not of normal occurrence the immigration of numerous malarial 



patients makes it of importance to take measures to reduce the chance 



of" their infecting the local mosquitos. Such patients should be prevented 



so far as possible from settling in fen lands and other low-lying districts 



where mosquitos are more numerous than elsewhere, and patients actually 



in such districts should during their attacks be kept in the seclusion of 



mosquito nets or gauze-screened rooms. 



-in via, the genus concerned in the spread of Yellow Fever and 



Deniuie Fever, is controlled by the methods already mentioned, but it 



should In: remembered that mosquitos of this genus are particularly 



prone (i) to breed in water-butts, old tins and other receptacles, and 



(2) to haunt the interior of houses and ships. In the latter case they 



>t cleared out by fumigation, 2 care being taken to paper up all 



chinks, to leave the room or cabin sealed up for three hours, and to burn 



arcntly dead mosquitos. 



The CHIRONOMIDAE include a large variety of Midges. The genus 



CktfonomuSf one of the commonest, has a worm-like aquatic larva which 



<:ies is coloured red by haemoglobin (" Blood-worms "). In 



the genus Culicoides or Ceratopogon the female is blood-sucking and is 



tii'- commonest type of blood-sucking midge or "sand-fly." In 



-"in- re-ions these midges are even more annoying than mosquitos, for 



mall size ordinary wide-meshed mosquito-nets are no 



protection against them, and owing to their occurring in swarms, not 



Might but only occasionally, immunity to their poison is not 



'|>cd so readily as in the case of mosquitos. 



i part, Kr<l Oil of Camphor 2. parts, Lanoline or 



I oil -1-5 parts (Hewlett). 



> >un.l of sulphur per thousand cubic feet of room. Burn in an iron 

 :i"'l with spirit. 



