Baker — New Aphid Injurious to Plum Trees. 



95 



mm., II, 0.048 mm., Ill, 0.304 mm., IV, 0.224 mm., V, 0.192 mm., VI 

 (0.112 mm. 4- 0.16 mm.). Segments imbricated but no secondary sensoria 

 present. Cornicles 0.32 mm. long, subcylindrical, slightly tapering, dis- 

 tinctly imbricated and without a distal flange. Cauda, 0.112. Three 

 pairs of very prominent lateral tubercles are present, one pair on the pro- 

 thorax, one pair between the middle and hind coxae and one pair caudad 

 of the cornicles. 



Alate Viviparous Female. 



Winged forms begin to appear with the first generation after the stem- 

 mother and may be found thereafter throughout the season. Pupae of the 

 first generation of winged forms are present during the first week in May, 

 while the apterous forms of the same generation are just beginning to 

 reproduce. 



Color brownish. Head, thorax and appendages black. Abdomen pale 

 brown with 5 rather large black patches on each wide. Caudad of the 

 cornicles three transverse bands of black are present which become more 

 or less fused. Cornicles sometimes with the extreme tip pale. Wing 

 veins heavy and margined with brown. 



Length from vertex to tip of cauda, 2 mm. Antennae as follows: Seg. 

 I, 0.048 mm., II, 0.408 mm., Ill, 0.24 mm., imbricated and armed with 

 5 or 6 subcircular sensoria forming an even row, IV, 0.208 mm., imbricated 

 but without secondary sensoria, V, 0.192 mm., similarly imbricated but 

 lacking secondary sensoria, VI (0.144 mm. + 0.176 mm.). Forewings, 

 2.3 mm. long and 0.96 mm. wide at their widest diameter. Hind wings, 

 1.52 mm. long. Wing veins heavy. Cornicles, 0.272 mm. long, subcylin- 

 drical and prominently imbricated. The distal extremity has no distinct 

 flange but is cut off squarely or rounded. Cauda about 1.28 mm. long. 



Table of Measurements of Alate Form. 



