The dock false-worm an The dock false-worm : an apple pest dockfalsewormapp265newc Year: 1916 16 BULLETIN 265, U. S. DEPARTMENT OF AGRICULTURE. genesis may take one of several forms. Unfertilized females will de- posit eggs which either will not hatch or will hatch and the resulting larva? will die before attaining maturity, or the larva? from such eggs will produce only male adults. The dock false-worm belongs to the latter class, the unfertilized females ovipositing normally and the eggs hatching and ultimately producing males. Great care was taken in rearing the dock false-worm to ascert
The dock false-worm an The dock false-worm : an apple pest dockfalsewormapp265newc Year: 1916 16 BULLETIN 265, U. S. DEPARTMENT OF AGRICULTURE. genesis may take one of several forms. Unfertilized females will de- posit eggs which either will not hatch or will hatch and the resulting larva? will die before attaining maturity, or the larva? from such eggs will produce only male adults. The dock false-worm belongs to the latter class, the unfertilized females ovipositing normally and the eggs hatching and ultimately producing males. Great care was taken in rearing the dock false-worm to ascertain the status of parthenogenesis in this species. Single pupa? were kept separate in glass vials, and females emerging from them were confined alone with the larval food plant. They appeared as eager to oviposit as those confined with males, and the average number of eggs deposited Fig. 5.—The dock false-worm: a, Superior saw blade of the ovipositor of adult female; b, inferior blade of ovipositor. Highly magnified. (Original.) by them was greater than that deposited by mated females. The period of development of all stages, as a rule, averaged somewhat shorter than that of normal individuals, comparison, of course, being made only with normal males developing under identical conditions. The figures for parthenogenetic individuals of the various broods are given below, under the heading 'Life-history studies,' where they are kept separate from the figures for normal individuals. Table I compares the period of development of normal males and partheno- genetic males of the first, second, and fourth generations. No parthenogenetic individuals of the third generation were reared. Table I.—Comparison of life cycle of normal and parthenogenetic males of the dock false-worm, Wenatchee, 1915. Generation. Second Fourth Origin of males. Normal Parthenogenetic Normal Parthenogenetic Normal Parthenogenetic Average number of days in- Egg Larval Pupal stage. stage. sta
Size: 2119px × 944px
Photo credit: © Bookend / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
