INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



103 



Fig. 83. — The lupine aphis. Macrosiphum albifrons Essig, 

 on stem and pod of lupine. Enlarged three times. (Author's 

 illustration, P. C. Jr. Ent. ) 



THE GREEN CITRUS PLANT LOUSE 



Macrosiphum citrifolii (Ashmead) 



(Siphonophora citrifolii Ashmead) 



(Fig. 84) 



Description.— This is a large green plant louse, about the size of 

 and greatly resembling the destructive pea aphis in color and shape. 

 Under the microscope it will be found that the tips of the cornicles 

 (honey-tubes) of the pea louse are perfectly plain, while there are 

 mosaic markings or reticulations on those of the green citrus louse. 



Life History.— The young insects appear on the tender shoots early 

 in April and are especially abundant on young orange trees in the 

 nursery. Winged and apterous viviparous females continue to appear 

 throughout the entire summer, but only in the spring and early summer 

 is this species a pest. 



