82 MISCELLANEOUS STUDIES 



Davidson reported this species as present on knotweed in the 

 vicinity of San Jose, under the name P. galeopsidis Kalt. Later he 

 followed Gillette in placing it as a synonym of R. hippophoaes Koch. 

 The author has never collected it, but has had access to specimens 

 from Davidson in San Jose, and Davis in Oak Park, Illinois. For a 

 full discussion of the synonymy of this species see Gillette's paper 

 listed above. 



102. Rhopalosiphum lactucae (Kalt.) 



Figures 277 to 285 



Kaltenbach, Monog. d. Pflanzenlause, p. 37, 1843. Aphis (orig. desc.). 

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



Records. Sonchus spp. ; Stanford University (Davidson); Stanford Univer- 

 sity, May to July, 1915; Walnut Creek, May, 1915 (Davidson); Berkeley, July, 

 1915; Lemon Grove, San Diego County, January, 1916; Biverside, January to 

 May, 1917; Los Angeles, April, 1917: Asclepias sp.; Corvallis, Oregon, November, 

 1913 (Moznette). 



This is a common species infesting the heads of sow thistle 

 throughout the San Francisco Bay region and southern California. 

 In November, 1913, G. F. Moznette took it on milkweed in Corvallis, 

 Oregon. This collection consisted entirely of alate females, that may 

 have been the sexupara. Inasmuch as the identity of this species is 

 doubtful there is given below a brief description drawn from speci- 

 mens of nine alates and eight apterae taken on Sonchus spp. at Stan- 

 ford University in May, 1915, in Walnut Creek in May, 1915, in 

 Berkeley in July, 1915, and in Lemon Grove in January, 1916, and 

 on Asclepias sp. in Corvallis, Oregon, in November, 1913. This latter 

 collection is by George F. Moznette of Corvallis. 



Alate viviparous female. Prevailing color is apple green with 

 the head dark green to black, the prothorax apple green, the thoracic 

 lobes black. The abdomen is apple green with three pair of dusky 

 marginal spots on segments one, two, and three, respectively, and 

 with a larger dusky patch on the dorsum of segments four, five, and 

 six, being between the cornicles. The cornicles and cauda are luteous 

 with the extreme tip of the former dusky. The antennae are dusky 

 throughout. The legs are luteous with the tarsi and tips of the femora 

 and tibiae dusky. 



The head is about twice as broad as long, with a distinct frontal 

 tubercle (fig. 278). The antennae are set on distinct tubercles and 

 are between one and one-fourth to one and one-half times as long 



