24 



Usinger: Introduction 



Instead of spreading larvicides over thousands of 

 acres of water without regard to kinds or numbers 

 of mosquitoes present, the concept of "species sani- 

 tation" was adopted. This required that trained 

 entomologists sample potential breeding areas at 

 regular intervals and report on the presence or absence 

 and relative density of the various species encoun- 

 tered. For disease vectors, control measures were 

 undertaken only when counts reached a predetermined 

 level. By this means, Aedes aegypti was eliminated 

 from Havana and other Latin American cities, Ano- 

 pheles quadrimaculatus was controlled in the vicinity 

 of war areas in the eastern United States during 

 World War II, and Anopheles freebomi was reduced 

 in and around military establishments in California 

 and other western states. 



To control mosquitoes effectively and economically, 

 then, requires the services of an entomologist and a 

 crew of trained inspectors. The duties of an ento- 

 mologist in a mosquito control program are outlined 

 as follows (Bureau of Vector Control Memorandum, 

 April 30, 1948): 



1. Accurate appraisal of the existing and potential 

 mosquito sources within and adjacent to the dis- 

 trict, with such information systematically recorded 

 on appropriate maps and records. This information 

 to be obtained by: 



a. Surveys of mosquito occurrence such as (1) prop- 

 erly chosen and collected resting stations, light 

 traps, and biting conditions; (2) systematic larval 

 dipping collections; (3) field observations inte- 

 grated to understand mosquito species ecology. 



b. Accurate identification and systematic recording 

 of species distribution in the district. 



c. Observations of species habitats (aquatic and 

 adult), applied to guide control operations. 



2. Evaluation of adequacy and efficiency of control 

 programs by: 



a. Coordination of the routine survey and section 

 survey findings with the over-all control program. 



b. Coordination of the observations of the inspectors 

 with operations of the control crews. 



3. Training of organization personnel through: 



a. Casual daily conversations with staff. 



b. Organized training programs to acquaint the 

 staff with mosquito species identification and 

 with the vulnerability of species as determined 

 by knowledge of their ecology. 



4. Testing of control methods, materials, and tech- 

 niques, to determine their reliability in obtaining 

 control and the degree of control. This is accom- 

 plished by: 



a. Comparisons of methods, such as aerosol vs. 

 spray; ground vs. aerial approach; adult control 

 vs. larval control. 



b. Testing of materials and determining their capac- 

 ities one against another, in fresh, foul, salt, 

 brackish, sunlit, and shaded water; also their 

 residual qualities, effects upon mosquito pred- 

 ators, and effects upon agricultural crops, live- 

 stock, beneficial insects. 



5. Assisting in the planning, preparation, and carrying 

 out of public relations and educational programs, 

 which in the long run serve to document the dis- 

 trict's activities by recording its history. This is 

 done by: 



a. Preparation of visual education matter, such as 

 graphs, maps, photographs, exhibits, educational 

 pamphlets. 



b. Preparation of publicity releases for newspaper 

 and magazine publication of the entomological 

 aspects of the district's operations. 



c. Preparation and delivery of talks about mos- 

 quitoes, their life histories, and habits, to 

 schools, service clubs, farm organizations, and 

 professional groups. 



d. Personal contacts and professional associations 

 which promote closer appreciation of the ento- 

 mological problems and the scope and objectives 

 of the entire control program. 



6. Immediate application of new methods, materials, 

 and techniques developed by contemporary ento- 

 mological, chemical, medical, and veterinary 

 workers through: 



a. Review and interpretation of the current literature 

 concerning mosquito control. 



b. Personal contact with research workers at pre 

 fessional meetings and institutions of higher 

 learning. 



7. Investigation of encephalitis, encephalomyelitis 

 and malaria cases, including epidemiological 

 analyses of their occurrence by: 



a. Keeping of spot maps. 



b. Correlation of cases with mosquito populations. 



c. Gathering of case histories. 



8. Assisting in district administration, particularly 

 in decentralized districts. 



Survey methods are of several standard types. 

 Adults may be caught while biting on the bare arms 

 or legs, or counts may be made of the landing rates 

 on trousers or dark cloth. However, counts in natural 

 resting places are preferred because they can be 

 standarized and visited at regular intervals. Favorite 

 resting places include hollow trees (intro. fig. 28), 

 sheds or barns (intro. fig. 29), the shaded undersides 

 of bridges, chicken houses, porches, tank houses, 

 and the like. Artificial resting places may be set up, 

 including cages baited with live animals, or plain 

 boxes (intro. fig. 30). The latter have proved to be 

 effective for sampling Anopheles mosquitoes in many 

 places. Another effective method for sampling the 

 populations of some species of mosquitoes is the 

 light trap. A very efficient and standardized type is 

 the so-called "American light trap" (Mulhern, 1953), 

 modified from the "New Jersey" type (intro. fig. 70). 

 Unfortunately, the light-trap method is not uniformly 

 effective for all apecies and varies in efficiency with 

 changes in climate. Likewise, none of the methods 

 mentioned above gives data that can be compared with 

 other samples in the same or different regions because 

 the factors that influence adult mosquitoes are extremely 

 local and elusive. In spite of these difficulties, 



