Walnut aphids in California . 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 asfollo
Walnut aphids in California . 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), mm.; width of body (maximum),0-48 mm.; expanse of wings (average), mm; antenna, joint I, mm.; joint II, mm.; joint III, mm.; joint IV, mm.; joint V, mm.; joint VI, ; filament, mm.; cornicles, ~Fig. 8.—Chrornapliis juglandicola: Winged male (appendages of left side removed), a, Left antenna. (Original.) Described from many individuals collected in 1911 and * 12 atSan Jose, Cal. Both the male and the winged viviparous female ~±ien disturbedhave a habit if jumping psyllid-like into the air. Their flight isgenerally in the form of a long spiral, and when disturbed they fly inan upward direction. EGG DEPOSITION. / As mentioned before, the first sexual females of the year remainlonger on the leaves after they have reached the adult state thanthose developing later. In 1911 eggs were not observed in thefield until September, or seven weeks after the first appearance ofsexual females. In 1912 some eggs appeared in August. This longperiod between the first appearance of the sexed females and the40859°—Bull. 100—14 3 18 BULLETIN 100, U. S. DEPARTMENT OF AGRICULTURE. earliest egg deposition may be explained by the fact that until latein August males are quite scarce and so th
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Keywords: ., bookcentury1900, bookdecade1910, bookidwalnutaphidsinca100davi
