Bulletin Volume 1-17

Bulletin Volume 1-17

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Description

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 edition. Excerpt: ...glance. The larvae are full grown in from eight to ten days and then change into dark-brown pupae (fig. 5). The identification of the pupae is somewhat more difficult than that of the larvae. Nevertheless, after a little experience a glance suffices to determine the pupae of Stegomyia fasciata from those of other mosquitoes, and especially from those which may be found in the same water with them. The chief characteristic is the narrower and more graceful thoracic portion, which in the Culex species is comparatively clumsy in appearance. The respiratory siphon of the pupae being slightly posterior to that of Culex, the bod' assumes a position horizontal with the surface of the water, with less curvature of the tail than has the genus Culex. The color of the pupa is much darker brown in Stegomyia; but. after all, the identification of that mosquito is Justus well made from the larvae, for they will be found at the same time with the pupae. The complete imago escapes from the pupa case in from one to two days. The entire metamorphosis is shorter in Stegomyia by two to three days than in Culex and is completed in from eight to ten days. The difference of time in each species, of course, depends upon the temperature and supply of food. In their characteristic breeding places the larva' and pupa1 have one trait that is of interest in connection with their destruction. When the barrel or other container with thousands of larvae is approached and slightly agitated, the insects disappear rapidly to the veiy bottom, so that nearly all the water can be dipped from the barrel without removing more than a few of the larvae. The barrel may be turned upon its side, and it will be found that about 80 per cent of the larva1 will stay in the few remaining ounces...show more

Product details

  • Paperback | 104 pages
  • 189 x 246 x 6mm | 200g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236547934
  • 9781236547934