A study of the seasonal distribution of Anopheles in Houston, Texas

Abstract

The problem of malaria in the South, and in other parts of the United States as well, has demanded a considerable amount of research. The greater part of this work has been concerned with the control of the disease by the eradication of the anopheline mosquitoes, and much of such work recently has dealt with the ecological aspects of the problem. Such factors as temperature, humidity, larval food, plant associates, hydrogen-ion concentration of the water of larval breeding places, and many others have been considered. The effects of these various factors on the life and habits of the mosquitoes usually differ for the various species and often differ for a single species in different parts of its range. Since the life of an animal is never entirely governed by a single factor, but by a complex combination of interrelated factors, each area studied offers to some extent a condition peculiar to the location. In the following pages an attempt will be made, after the plotting of fluctuations in the seasonal abundance of the one common Anopheles of the region, Anopheles quadrimaculatus Say, to evaluate the various ecological factors involved in producing these fluctuations. It will be shown that the influence of some of these factors is of very local nature; that is, certain factors may operate in quite different manners and may be of decidedly different importance in a locality where a bayou is the main source of emerging mosquitoes, on the one hand, and in a nearby locality where flooded rice fields are the main source. This survey covered the period of time from March 1932 to January 1934. The area studied included the southern part of the city of Houston and immediate vicinity outside the city limits, and also a rice farming district 15 miles to the west of the city