53 



be effected in tlie interior of courtyards, gardens and in the imme- 

 diate neighbourhood of dwellings. These mosquitos again are of 

 secondary consequence. 



(4) Mosquitos Breeding in Domestic Utensils. — The larvae of 

 mosquitos which are found in the midst of inhabited centres 

 either in abandoned domestic utensils, or even those which are 

 actually in use, are those which especially demand the attention 

 of the sanitary staff. By far the largest proportion of the mos- 

 quito larvae found in the water collected in these vessels, are 

 the larvae of Stegomyia and the sanitary staff should examine 

 all pails, barrels, jars, cisterns 'and every kind of article, how- 

 ever small, capable of containing water, in the interior or in the 

 neighbourhood of houses; empty tins, the bottoms of railway 

 waggons, all hollow bricks, in fact, everything that by any possi- 

 bility could contain a little water. The detection of the larvae 

 is not always easy at first. The members of the sanitary staff 

 frequently conient themselves with the examination of a sample 

 of water taken from a suspected receptacle. This plan is utterly 

 insufficient and thoroughly bad. The receptacle itself must be 

 carefully examined throughout, and, if need be, removed from 

 its position into full daylight, so that there shall be no doubt of 

 the thoroughness of examination. The members of the staff 

 should be accustomed to this mode of operation, which is often 

 not altogether acceptable to the inhabitants of the houses. The 

 existence of a wood, metal, stone or even a cement cover to a 

 vessel containing water should not be regarded as sufficient excuse 

 for omitting the same thorough examination, for, unless such 

 covers are absolutely air-tight, there is sure to be some crack 

 through which the mosquito can find access to the water within. 

 The presence of larvae is very frequently announced before the 

 examination, by mosquitos flying out of the vessel when the cover 

 is lifted. The greatest attention should be paid to receptacles 

 which are constantly placed in the shade. Those which are fully 

 exposed to the sun, especially if of metal, are not worth inspect- 

 ing, but if there be any that have deposits of moss or of algae 

 on their sides, inspection should be thorough. A^essels in which 

 the water is constantly fouled by dust in sufficient quantity to 

 form a deposit on the surface rarely contain any larvae. In 

 villages, tubs and jars used for the preparation of indigo should 

 be specially investigated. The time required for the fermenta- 

 tion of solutions of indigo is 10 days. It will therefore he suffi- 

 cient, and will prevent interference with the native industry, if 

 care be taken that the solutions in these tubs is renewed every 

 10 days. Irrigation cuttings should be inspected with care, 

 especially if there is any tendency for the water to stagnate, but 

 in these and smaller channels if the water is renewed and circu- 

 lates for at least a few hours per diem, the larvae will not develop. 

 The spathes of pineapples, bananas, coconut palms and garden 

 plants do not require much attention, because the number of 

 larvae which can develop in them is trifling compared with those 

 found in other places more easily controlled. All holes in trees 

 should be most carefully examined. Wells with cemented sides 

 should be looked after, especially if not in use, whether they have 

 a cover or not. Wells which are lined with hollow bricks or badly 



