Zoological Bulletin Volume 6

Zoological Bulletin Volume 6

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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. 1908 edition. Excerpt: ...the same as in fields, orchards and woods. III. 3. Duration in the Pupal Stage. The length of time that an insect may exist in the pupal stage becomes important as indicating the possible number of broods in a year in any one region. There are some species, like certain flies. which may exist in the pupal stage but a very few days, while others, such as Plum Curculio, transform in early summer and remain quiet during the remainder of the summer and autumn and during the entire winter. Those with hort pupal stages may, of course, produce several broods or generations per year, and are consequently more liable to become very numerous and, therefore, objectionable. It should be remembered that the date of pupation is not exactly the same as the date when the larva quits feeding, as it often requires a few days to get rid of the undigested food substances, and beeome shorter and thicker, before casting its larval coat for the last time and assuming the true aspect of a pupa. Also, it must be remembered that many insects, such as the Codling Moth and Sawflies, of which the currant worm is a representative, may spin cocoons over themselves after they cease the active larval existence, but remain as quiet larvae inside these during the entire fall and winter, not transforming to the chrysalis until toward spring. Thus the date of the spining of the cocoon does not always mean the date of real pupation of its in-mate. These are points which should be carefully watched by an accurate and-exact student. III. 4. Place of Pupation. The study of the place of pupation becomes of the utmost importance from a scientific and practical standpoint. It is interesting and remarkable that some insects, such as the butterflies, form naked or unprotected...
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Product details

  • Paperback | 156 pages
  • 189 x 246 x 8mm | 290g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236771524
  • 9781236771520