INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 77 



THE BEAD-LIKE COTTONWOOD GALL-LOUSE 



Tecabius populimonilis (Riley) 

 (Pemphigus populimonilis Riley) 



Description.— The body is dark and covered with rather long white 

 flocculence, which gives it a bluish appearance. The presence of 

 this species is easily told by the very characteristic reddish, bead- 

 like or almond-shaped galls formed on the margins and centers of 

 the leaves of the cottonwood trees which it infests. 



Life History.— According to Professor C. P. Gillette 50 the eggs are 

 probably laid on the cottonwood trees in the fall and hatch the 

 following spring into the stem-mothers. These settle on the young 

 leaves between the midrib and the margin and produce almond- 

 shaped or bead-like galls. The young from the stem-mothers also 

 locate on the tender leaves and cause similar galls. Nearly all of 

 these are winged and many migrate to other leaves and trees, there 

 being a third generation arising from the winged forms whether 

 they migrate or remain in the original galls. In the latter case as 

 many as twelve young may be found in a gall with the parent. 

 These young mature in the fall and give birth to the sexual forms, 

 which mate and the females lay the overwintering eggs. The sexual 

 females are pale green and the males yellow. Neither have rostrums 

 or beaks for feeding. 



Distribution.— This species occurs throughout the State, wherever 

 the host plants grow, but appears to be more abundant in the southern 

 part. 



Food Plants. — The common cottonwood (Populus t rich o carp a) , Pop- 

 ulus fremontii, P. oalsamifera var. angustifolia, are attacked. 



THE SOLANUM ROOT PLANT LOUSE 



Trifidaphis radicicola (Essig) 

 (Pemphigus radicicola Essig) 



Description.— The apterous female is distinctly globular in shape 

 and varies from amber to cream-color and often has a fine, white, 

 powdery covering. The winged form is amber with dark head and 

 thorax. The wings are dusky. The length varies from 1-25 to 1-12 

 inch. 



Life History. — This species is subterranean in habits and is evident 

 during the early spring and the entire summer. The winged form 

 appears in July and August. It has not been determined whether 

 the species hibernates in the egg stage or as viviparous females or 

 as both. 



Distribution. — This species occurs throughout the central and 

 southern parts of the State and is especially abundant in the south. 



Food Plants.— Roots of nightshade (Solatium douglasii), pigweed, 

 and potato tubers are attacked. The alternate host has not been 

 discovered. 



"Ann. Ent. Soc. Am., VI, No. 4, pp. 485-492, 1913. 



