INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 99 



as the large rose aphis, Macrosiphum rosce Linn., for which it is often 

 mistaken. 



Life History.— It is a very serious rose pest at times, and espe- 

 cially bad in the summer months, breeding very rapidly and collect- 

 ing in great numbers upon the leaves. It works throughout the 

 summer and is the worst rose pest in many parts of the State. 



Fig. 80, 



-The small green rose aphis, Myzus rosarum (Walk.). Winged and apterous 

 females greatly enlarged. (Author's illustration, P. C. Jr. Bnt. ) 



Nature of Work.— All stages attack the young buds, tender shoots 

 and the old hardy foliage of the bushes, preventing a normal pro- 

 duction of flowers, and secreting quantities of honey-dew which covers 

 the bushes and furnishes a medium of growth for the black smut 

 fungus. 



Distribution. — This species occurs throughout the entire State. 



Food Plants. — All varieties of roses are attacked. 



Natural Enemies. — Syrphid flies do considerable work upon this 

 species, but the natural enemies are not numerous enough to check 

 the ravages until after most of the damage is done. 



THE PARSNIP PLANT LOUSE 



Siphocoryne caprew Fabricius 64 



[Hyadaphis caprew (Fabricius)] 



(Rhopalosiphum caprew Fabricius) 



(Fig. 81) 



Description.— The apterous females are pale green and sometimes 

 have a few small red spots on the dorsum. The winged forms are green 

 with the head, antennae, thorax, middle dorsum of the abdomen, tips of 

 the cornicles and the leg joints dark or black. This species may be dis- 

 tinguished from a closely related species, Siphocoryne pastinacce 

 (Linn.), by the presence of a small tubercle just above the Cauda or 

 tail. This tubercle is entirely absent in the latter. 



"There is some difference of opinion regarding the position of this species. Prof. 

 C. P. Gillette places it in the genus Rhopalosiphum (Jr. Ec. Ent., IV, p. 320, 1911), 

 while J. J. Davis puts it in the genus Hyadaphis (Jr. Ec. Ent., Ill, pp. 493-494, 1910). 

 H. F. Wilson considers the genus Siphocoryne correct. All previous references to 

 Hyadaphis pastinacw (Linn.) by the writer should have been to this species instead. 



