Observations on the Macroscopic Species-Identification of Larval Anopheles in Georgia

Abstract

In most places where routine surveys of local Anoopheles distribution have been undertaken by large scale collection and identification of larvae from nearby aquatic situations, a certain familiarity the larvae has probably developed. The familiarity, in some cases, has been developed into a technique for distinguishing the larvae of the local species by their macroscopic appearance. Dr. W. V. King, Bureau of Entomology and Plant Quarantine, U. S. Department of Agriculture, related (in lectures to malaria entomology trainees at Orlando, Florida, 1937) that Philippine assistants learned in their country to distinguish macroscopically, a high degree of accuracy, the larvae of different species of Anopheles occurring there. Dr. Arnaldo Gabaldon, Division de Malariologia, Direccion de Salubridad Publica, Ministerio de Sanidad y Asistencia Social, Caracas, Venezuela, stated (in personal communication) that, in Venezuela, sanitary inspectors may learn to distinguish macroscopically the larvae of anopheline species encountered in a small area but that this ability is lost if they are transferred to a new area. Dr. D. Bruce Wilson states (in a manuscript report to the International Health Division of the Rockefeller Foundation, 1940) that in the campaign against Anopheles gambiae in Brazil, a technique was developed for distinguishing macroscopically the larvae of this species from larvae of the Brazilian Anopheles of the subgenus Nyssorhynchus. D. Manson (1934) has tabulated certain macroscopically visible characters of the larvae of eighteen species of Indian Anopheles as an aid to the macroscopic identification of these forms, and states that a short period of training and attention to detail one may learn to distinguish larvae of the more common species of Assam Anopheles with a considerable degree of accuracy. A few months after inauguration of Anopheles survey work in South Georgia, it was noted that the presence or absence of larvae of Anopheles quadrimaculatus in collections was usually correctly anticipated in the