A sanitary inspector, when malaria is rife, has to be thoroughly familiar with the life history of the mosquito, and particularly with the life history of the anopheles. There are some six or seven hundred species of mosquitoes, and many of these differ widely in their habits of flight. The stegomyia mosquito is one of the feeblest species in its ability for flight, and it is at once blown away and destroyed when it gets into a breeze. It therefore seldom wanders from the house in which it is bred. The culex solicitans is very strong and bold in flight, and can fly twenty miles in one night before a favoring breeze. This has been demonstrated by Dr. J. B. Smith, of New Jersey. Dr. Smith was the entomologist of the state of New Jersey, and one of the most faithful and successful mosquito workers. The culex solicitans is the common gray mosquito which breeds so abundantly in the salt-water marshes of our Atlantic coast. The different species of mosquitoes differ widely as to their breeding-places, some species breeding in brackish water, some only in fresh water. Other species breed freely in dirty and muddy water, and still others can apparently live only in fresh, clean water. The two species with which we are most concerned as being disease-carrying mosquitoes are very particular as to their habits, always seeking fresh, clean, clear water in which their larvæ can develop. The stegomyia likes clean rain water such as is found in cisterns and water barrels. As these collections are found principally around the dwellings of man in towns and cities, this mosquito is known as a town mosquito. The larvæ of the anopheles, the malarial mosquito, also likes clear, clean, fresh water, but it requires algæ and grass for its protection. These conditions are best furnished by the edges of ponds and running streams. This mosquito is, therefore, essentially a country mosquito. Generally, in any one locality, there are only three or four species of mosquito occurring in any abundance, so that when the inspector has learned to differentiate these, he is pretty well educated for work in that particular locality. Each species usually has some prominent trait; the anopheles, for instance, has the hind legs very much longer than the fore legs, which gives her when at rest the appearance of standing on her head. The stegomyia has prominent white markings on its body and white bands around the joints of its legs, and while these cannot readily be distinguished by the naked eye, they give it a gray appearance which easily distinguishes it from other species in such a locality as Panama.