. Bulletin of the Department of Agriculture. Agriculture. WALNUT APHIDES IN CALIFORNIA. 21 individuals of this generation of which the date of deposition had been ascertained. Individuals of the fourth generation probably mature in an average of 16 days. The" leaves of the Eastern black walnut fall earUer than those of the European or California black types, and consequently the viviparous apliides are not found so late on the trees. There are probabl^^ not more than nine generations of these in a year. Immediately after passing the final molt the aphides begin depos- iting young. Th
. Bulletin of the Department of Agriculture. Agriculture. WALNUT APHIDES IN CALIFORNIA. 21 individuals of this generation of which the date of deposition had been ascertained. Individuals of the fourth generation probably mature in an average of 16 days. The" leaves of the Eastern black walnut fall earUer than those of the European or California black types, and consequently the viviparous apliides are not found so late on the trees. There are probabl^^ not more than nine generations of these in a year. Immediately after passing the final molt the aphides begin depos- iting young. These are entirely pale lemon-yellow with red eyes and four longitudinal rows of capitate hairs and do not exceed mm. in length. From 10 to 20 young are produced by a single female, dependent on the season of the year. The earher generations are more prohiic. After midsummer the progeny becomes smaller and smaller with successive broods. THE PUPA OP THE WINGED VIVIPAROUS FEMALE (PIG. 9). After the second molt the pupal wing pads are apparent as small emarginations on the sides of the thorax, but after the fol- lowing molt they are much more readily seen. The pupa of the winged viviparous female may be described as follows: Color generally pale lemon-yellow, sometimes white; head often with a reddish tinge. Antennse on small frontal tubercles, pale yellow, with the filament and articulations of joints 3 to 6 dusky black. Eyes bright red. Thoracic segments and wing pads light yellow, wing pads projecting out from the body at a very acute angle. Legs pale, tarsal apices dusky. Body beset with long capitate spines in four rows. Cornicles on segTaent 6 of the abdomen, hardly perceptible, broader than long. Cauda blunt, conical, and short. Cornicles and cauda concolorous with the abdomen. Beak pale, reaching to the middle coxae. Measm-ements: Length of body (average), mm.; width of body (average), mm.; antenna, joint I, mm.; joint II, mm.; joint III, mm
Size: 1541px × 1622px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectagriculture, bookyear
