Bulletin of the U.S. Department of Agriculture Volume 801-812 download book

Bulletin of the U.S. Department of Agriculture Volume 801-812. United States Dept Agriculture

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Author: United States Dept Agriculture
Page Count: 182 pages
Published Date: 13 Sep 2013
Publisher: Rarebooksclub.com
Publication Country: United States
Language: English
ISBN: 9781236929570
File size: 32 Mb
Download Link: Bulletin of the U.S. Department of Agriculture Volume 801-812
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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. 1922 edition. Excerpt: ... and 15 days, respectively. Second-brood adults appear on the trees from the middle of July until about a month later. The third-brood eggs hatch from July 30 until about September 1, the length of the egg stage of this brood being about 9 to 10 days. Third-brood nymphs are found on the foliage from August 1 until about the third week in September, the average length of the entire nymphal period being 18.7 days or approximately the same as that of the first brood. By the middle of August the nymphs begin to transform to adults and by the end of September all the nymphs have disappeared. The third-brood adults remain on the trees until cold weather sets in when they gradually disperse to the hibernating places. NATURAL ENEMIES. The apple leafhopper is evidently quite free from the attack of parasites. Only one record of parasitism has appeared in the literature, Pc. L. Webster in 1913 having noted the pupa of an egg parasite which, however, died before reaching maturity. A few cases of parasitism of adults by a dryinid have been seen at West Chester, Pa., but no adults of this parasite were reared successfully. However, two dryinid females were captured in the field while in the act of ovipositing in the abdomen of nymphs of Empoasca mali. These specimens were determined by Mr. J. C. Crawford, of the United States National Museum, as ApTielopus albopictus Ashm. Probably the most effective enemy of this leafhopper is the predacious heteropteron TripMeps insidiosus Say. This small black insect, which is rather common on the foliage during midsummer, feeds on the nymphs by thrusting its beak into their soft bodies. It is actually of little importance, however, in reducing the numbers of leafhopper nymphs. Spiders and various species of mites...

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