Of all the measures designed to effect a reduction in the number of mosquitos “ oiling,” or the application of kerosene in one form or another to collections of water in the neighbourhood, is I suppose the favourite. The popularity of this measure is no doubt an indication of its general efficiency, and as it is a remedy that can and should be employed by the individual as well as by the Sanitary Authorities, it has become familiar to every dweller in the tropics. This familiarity has, I believe, led to an exaggerated confidence in its efficacy.