In all probability some moths would have to be released each year in a continuing 

 program to prevent reestablishment of long-range migrants from other areas. Such 

 maintenance programs should, however, cost much less than the yearly operations 

 during the first 2 years, which are designed to achieve complete control over the 

 original population. 



Again, these projections for controlling the tobacco hornworm are mere estimates 

 based on a hypothetical situation. There is reason to believe, however, that they 

 reasonably reflect what could be achieved in the application of this technique, once fully 

 developed and perfected. If the estimates are reasonably valid, the total program would 

 cost less than the expenditures for controlling the insect each year, but in addition all 

 losses caused by the pest should be eliminated completely. 



Tsetse Flies 



In appraising the sterility principle for controlling or eradicating tsetse flies, 

 advantage has been taken of every opportunity to review literature and discuss tsetse 

 fly biology, ecology, and behavior with experts in the field. 



Scientists working on tsetse flies have obtained much valuable basic information 

 on the biology, habits, ecology, and population dynamics of the various species in 

 Africa. Additional information is needed, however, on pertinent aspects of the biology, 

 ecology, behavior, dispersion, and population densities of the various species in rela- 

 tion to the sterile-insect-release technique before a full appraisal can be made of the 

 potential value of the method. Information is needed on ways to produce sterility in 

 various species. Methods of rearing, or efficient methods of trapping the insects must 

 be developed. However, the writer is confident that the sterility method offers a pro- 

 cedure that can be developed so that it will be of great value in tsetse fly control and 

 eradication programs. 



The same general approach in estimating the value of the sterile-insect-release 

 technique for other insects has been followed in appraising the sterile-male method for 

 tsetse fly control or eradication. 



In making this appraisal, the writer has drawn heavily on the compilation by 

 Buxton, which discusses almost every aspect of the biology, ecology, and control of the 

 tsetse flies. The writer also wishes to acknowledge, with appreciation, the opportunity 

 to discuss, or communicate on, matters of tsetse fly biology, ecology, behavior, 

 rearing methods, and current control procedures with such authorities as J. Ford and 

 his associates of the Department of Veterinary Services, Federation of Rhodesia and 

 Nyasaland, Salisbury; W. H. Potts, Commonwealth Bureau of Entomology, London, 

 England; P. E. Glover and W. P. Langridge, Kenya Veterinary Department, Kabeta; 

 K. S. Hocking, Tropical Pesticides Research Institute, Arusha, Tanganyika; and 

 J. P. Bernacea, Uganda Department of Veterinary Services, Entebbe. 



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