8t> MISCELLANEOUS STUDIES 



of Prunus are the winter hosts in Colorado, while during the summer 

 it migrates to other plants. In California, however, winter eggs are 

 not laid, the viviparous females living the year round. So far as the 

 author has observed in over three years, only the form with clavate 

 cornicles is found in California. 



105. Rhopalosiphum rhois Monell 



Figure 173 



Monell, U. S. Geol. Geog. Surv., Bull. 5, p. 27, 1879 (orig. desc.). 

 Davis, Can. Ent., vol. 46, p. 165, 1914. E. Iwwardi (Wils.) (desc.). 

 Essig, Univ. Calif. Publ. Ent., vol. 1, p. 330, 1917. B. howardi (Wils.) 



(list). 

 Ibid., p. 334, 1917 (list). 



Eecords. Ehus diversiloba; Berkeley, April, 1915; Avena sativa, Berkeley, 

 (Essig). 



This species has been taken in Berkeley on poison oak and grasses. 

 Essig reported it recently as R. howardi (Wils.), but according to 

 Gillette 14 this is a synonym of R. rhois Monell, Rhus being the winter 

 host, and various species of GramMiaceae the summer hosts. 



This species does not seem to be a typical Rhopalosiphum, being 

 quite close to Siphocoryne nymphaeae Linn., but yet not fitting the 

 generic description of Siphocoryne exactly. Consequently it is best 

 to list it as has been done heretofore as Rhopalosiphum. . 



106. Rhopalosiphum violae Pergande 

 Figures 164, 174 



Pergande, Can. Ent., vol. 32, p. 29, 1900 (orig. desc.). 

 Essig, Pom. Jour. Ent., vol. 1, p. 4, 1909 (desc.). 

 Davidson, Jour. Econ. Ent., vol. 2, p. 303, 1909 (list). 

 Davidson, Jour. Econ. Ent., vol. 3, p. 277, 1910 (list). 



Eecords. Viola spp. ; Claremont, Santa Paula (Essig); Stanford University 

 (Davidson); Palo Alto, May, 1915; Santa Ana, February, 1917; Eiverside, April, 

 1917. 



This beautiful little aphid is found more or less abundantly in the 

 spring on the under side of the leaves of violets throughout the state. 

 The dark red color and broad black wing veins serve to distinguish it 

 readily from other aphids. 



Gillette, Jour. Econ. Ent., vol. 8, p. 100, 1915. 



