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ECONOMIC IMPORTANCE OF MOSQUITOES

THE GENERAL ECONOMIC IMPORTANCE OF MOSQUITOES[1]
By Professor JOHN B. SMITH

RUTGERS COLLEGE, NEW BRUNSWICK

NO one should be better qualified than a Jerseyman to speak on this subject, for no state in the union has suffered more in reputation and in arrested prosperity from mosquitoes than New Jersey.

During the four or five years last past, I have had opportunity to observe conditions closely, and there is not a section whose development has not been in some way affected by this insect pest.

First: by the carriage of malarial disease, and by the term carriage, I mean, of course, not the direct transmission from one individual to another, but that service as intermediate host in the development of the parasitic organisms that cause the disease.

Anopheles occurs throughout our state, although the A. maculipennis, which is the only one of our species known to be affected by the parasite, is comparatively rare and is, curiously enough, more abundant in the more northern, hilly portions than in the southern lowlands, where breeding places are more numerous.

Malarial diseases are much less common with us than they were a few years past, and that is due partially to the improvement of sanitary conditions which lessens mosquito breeding in densely populated districts, and partly to the much more thorough treatment which a patient now receives from the attending physician.

It requires the presence of a patient infested with the plasmodium, as well as of the proper species of Anopheles, to start an epidemic of malaria, but the mosquitoes need not be at all common to make trouble. I have in mind an instance very much in point: A village of high-class residences, well-located, generally healthy and where mosquitoes were accounted among the rarities; but, as it happened, the few that did occur were A. maculipennis. Into that community, where no case of malaria had ever been known, was introduced a gang of Italian laborers, recent immigrants, it was later found, and most of whom had been affected with the fever in Italy.

Before the end of the season a considerable number of cases of the æstivo-autumnal variety had developed in the village and some of them of the most severe type. This led to a search for the cause, and the breeding places for the few mosquitoes that occurred were located and abolished. Italian laborers have been tabooed in that

  1. Read at a meeting of the American Society of Tropical Medicine, Philadelphia, December 7, 1906, and published under its imprimatur.