Bulletin of the U.S. Department of Agriculture Volume 326-339

Bulletin of the U.S. Department of Agriculture Volume 326-339

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1916 edition. Excerpt: ...on these points may be obtained in the following three ways: (1) By rearing adult females from the immature stages, and then allowing them to engorge, oviposit, and reengorge. This method was tried a number of times, but with no success, for the fly will not readily engorge while in captivity, as was noted in the discussion of the feeding habits of the adult (2) By the capture of adults actually feeding on mammals, and by inducing them to oviposit and then to reengorge. This method also was unsuccessful for the same reasons. (3) By dissections. If it could be proved that when a Simulium, which has once engorged on blood and oviposited, is still in a condition favorable to a second oviposition--that is, if rudimentary eggs are present in the ovaries awaiting only a second blood meal for their successful development--then there would be a more definite basis for a theory of disease transmission as opposed to the theory of merely a close coincidence in the distribution of pellagra and Simulium. This is the method adopted by the writer and is the one discussed in the following pages. The experiments were concluded in Spartanburg County, S. C, a country very favorable for the production of Simulium, being hilly and with a network of small streams, rapid and especially suitable for the development of the immature stages. The experiments on the actual biting and feeding habits were carried on more or less continuously from June 13 to September 16. The material for these experiments consisted of specimens of S. venustum; a good series of reared specimens (about 30); a number of females found engaged in oviposition; about 300 females all of which were taken in the act of engorging on mammals. Of the last named only about 90 were successfully...show more

Product details

  • Paperback | 240 pages
  • 189 x 246 x 13mm | 435g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236805585
  • 9781236805584