The Black Fly of Citrus and Other Subtropical Plants

The Black Fly of Citrus and Other Subtropical Plants

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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. 1920 edition. Excerpt: ...forth through a slit along the median dorsal surface of the egg, the brown eggshell remaining plump and often very confusing as the slit seems to close again. Drying out of the leaves on which the eggs are laid seems to kill them, until one or two days before they are ready to hatch, as is shown later. FIRST LARVAL INSTAR. The larva that emerges from the egg is rather elongate ovate in shape, whitish in color, with reddish eye spots, short antennas, and rather short legs. It crawls around sluggishly for from two to four hours and then settles down, the farthest distance crawled, out of 580 individuals, being 1 inches from the center of the egg spiral. But fully 80 per cent of the larvae never crawl more than one-half inch away from the spiral from which they emerge. On settling down the larva describes an arc of from 75 to 120 degrees, evidently to help in inserting its thread-like rostral setae into the tissues of the leaf. This movement seldom lasts more than 20 minutes. Two hours after emergence from the egg the larvae are dusky all over, with the exception of the margins, and within four hours they are fully colored, i. e., blackish, and more broadly ovate than on emergence. There is a tendency for them to flatten out. There is a pronounced median ridge, on each side of which, anteriorly and posteriorly, are four long dorsal spines and numerous shorter ones. Larvae that have settled once have been observed to change their position and go through the same rotating movement on settling down again. On leaves bearing large numbers of spirals or on small leaves, as in the case of orange jessamine (Chalcas exotica), the larvae seem to show a tendency to settle down along the smaller veins of the leaf and parallel to them, but this position...show more

Product details

  • Paperback
  • 189 x 246 x 1mm | 64g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236834429
  • 9781236834423