File:Walnut aphids in California (1914) (14780612634).jpg

Identifier: walnutaphidsinca100davi (find matches)
Title: Walnut aphids in California
Year: 1914 (1910s)
Authors: Davidson, W. M. (William Mark), 1887-
Subjects: Aphids Walnut Diseases and pests
Publisher: Washington, D.C. : U.S. Dept. of Agriculture
Contributing Library: U.S. Department of Agriculture, National Agricultural Library
Digitizing Sponsor: U.S. Department of Agriculture, National Agricultural Library

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Text Appearing Before Image:
ons of joints III to XI duskygray. These dark articular annulations are less pronounced than in the viviparousfemale. Wings of medium size; costa, subcosta, and insertions pale yellowish gray:stigma short and gray, with its central area paler; veins gray, second fork of thirddiscoidal nearer to the wing apex than to the first fork and arising beyond the apexof the stigmatic vein; stigmatic vein evenly and gently curved, absent in the middlefor a space equal to one-third of its length. Legs longer in proportion to the body thanthose of the other forms; front legs and middle tibiae very pale yellow or yellowishgreen; distal two-thirds of the middle and hind femora shaded gray, the black kneespot being present on these four femora: hind tibiae shaded gra> for its proximal three-fourths, its apical fourth pale yellow; all tarsi light gray. Abdomen barely as longas the head and thorax combined, widest at the fourth segment, and with a pair of il. TOO, U. S. Dept. of Agricultur PLATE II.
Text Appearing After Image:
Eggs of European Walnut Aphis (Chromaphis juglandicola) onPiece of Bark of European Seedling Walnut. Twice NaturalSize. WALNUT APHIDES IN CALIFORNIA. 17 oval gray transverse spots on the fifth segment, which are separated by a space equalto their length. Cornicles pale yellow, about as broad at the base as long, very muchas in the winged female. Cauda pale yellow, globular, not quite as long as the hindtarsus. Sexual organ pale yellow. Beak pale yellow, slightly exceeding the forecoxse. Sterna black. Sensoria transversely oval, situated in an irregular row asfollows; joint III, 11 to 16; joint IV, 5 to 7; joint V, 4 to 5; joint VI, 2 besides usualterminal. Measurements: Length of body (average), 1.47 mm.; width of body (maximum),0-48 mm.; expanse of wings (average), 4.20 mm; antenna, joint I, 0.05 mm.; joint II,0.04 mm.; joint III, 0.34 mm.; joint IV, 0.12 mm.; joint V, 0.12 mm.; joint VI, 0.08mm.; filament, 0.03 mm.; cornicles, 0.05 mm.

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