By working on the above lines, especially where one has the co-operation of neighbours, it is in all cases quite possible to materially diminish the nuisance of mosquitoes, and under favourable circumstances to practically extirpate them; though, in a usual way, complete success must not be expected. In the exceptional cases where this is possible, there is, of course, no need for the adoption of any other sort of measures; but, in the majority of cases, an amelioration only in the numbers of insects is all that can be attained; and it is necessary to guard against the risk of some of the survivors becoming infected, by the adoption of measures of the second and third classes. Of these the second, _i.e._, the protection of man from mosquito bites, is in most cases the most easily practicable. A variety of ointments and applications of various sorts have been from time to time vaunted as protectives, and the presence of certain plants, such as the eucalyptus and the castor-oil shrub, have also been stated to be so obnoxious to mosquitoes of all sorts that they might be trusted to make themselves scarce wherever these plants might be found. For these ideas there is doubtless this much foundation in fact, that most strongly smelling bodies really are obnoxious to mosquitoes; but unfortunately, whatever objection they may have to strong scent is not very deeply rooted, and in default of more congenial shelter they will settle upon either eucalyptus or castor-oil plants, and will brave even the hated smell of paraffin to secure a good feed on the blood of a human or animal subject. All these special applications to the skin, too, have the further disadvantage that, though some of them are fairly effectual for a few minutes after they have been just applied, and so enable the user to get sleep, they leave those who are deluded into depending upon them to fall unresisting victims, as soon as the thick of the scent has evaporated. So that, though valuable for securing rest, they are worse than useless from the point of view of the prevention of malaria. With these untrustworthy exceptions, all available measures are of a mechanical character, and consist in modifications of our housing and clothing.