104 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Fig. 84. — The green citrus plant louse. Macrosiphum citrifolii (Ashm. ). Apterous 

 and winged females. Greatly enlarged. (Author's illustration, P. C. Jr. Bnt.) 



Distribution. 



California. 



It occurs throughout the citrus belt of southern 



Food Plants. — The green citrus plant louse occurs especially abun- 

 dant on young orange seedlings and on suckers of large seedling orange 

 trees. It is probable that the older foliage of most of the orange trees 

 is also attacked. 



Natural Enemies.— The larvae of the predaceous ladybird beetle 

 (Hippodamia convergens) feed upon this insect in limited numbers. 

 The most efficient predators, however, are the larvae of the green lace- 

 wing (Chrysopa calif ornica) and the large syrphid fly (Syrplius 

 pyrastri). The internal parasite Charips xanthopsis also preys upon it. 

 The internal parasite, however, is probably only secondary. 



THE DESTRUCTIVE PEA APHIS 



Macrosiphum pisi (Kaltenbach) 



[Macrosiphum destructor (Johnson)] 



(Necturophora pisi Kaltenbach) 



(Fig. 85) 



Description. — The adult is a large, pea-green aphis, easily dis- 

 tinguished by the long legs and antennae. The head and thorax of 

 the winged forms are pinkish or yellow while there are no markings 

 on the apterous female. 



Life History.— This species feeds practically throughout the year 

 on perennial legumes like alfalfa and clover as well as the annuals 

 used for cover crops during the winter and upon the annuals as 

 peas, etc., during the summer months. They are exceedingly prolific 

 and often very destructive, especially to crops of peas. The winter 

 is either passed as immature or adult viviparous females as indicated 

 above or as eggs deposited on the perennial hosts. 



Distribution. — The destructive pea aphis occurs throughout the 

 entire State. 



Food Plants. — Alfalfa, clover, fenugreek, garden and field pea, 

 vetch and other legumes are attacked. 



