100 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



Distribution.— This plant louse is widely distributed throughout 

 the State. 



Food Plants. — The parsnip plant louse like its close relative, 

 S. past inane (Linn.), attacks only plants belonging to the Umbelliferce 



Fig. 81. — The parsnip plant louse, Siphocoryne caprece (Fab.) Apterous 

 and winged viviparous females. Greatly enlarged. (Author's illustration, 

 P. C. Jr. Ent.) 



and the willows, including Angelica sylvestris, A. atropurpurea, cara- 

 way, carrot, celery, Chwrophyllum tcmulum, goutweed, water hemlock, 

 Ligusticum porteri, treacle mustard, parsley, parsnip, cow-parsnip, 

 Pimpinella magna, willow (many species) and Zizia aurea. 



The sexual females lay the over-wintering eggs on the willow, upon 

 which the spring broods feed. Winged forms migrate later to other 

 plants, where the summer is passed, and still others migrate again to 

 the willow in the fall, to give birth to sexual forms, which lay the 

 winter eggs. 



