INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



81 



THE MOTTLED COTTONWOOD PLANT LOUSE 



Thomasia popuUcola (Thomas) 



(Chaitophorus popuUcola Thomas) 



(Fig. 63) 



Description. — The adult is dark red or wine-colored, often appear- 

 ing nearly black, and is distinguished from other poplar plant lice by 

 the clouded wings. The winged form is much darker than the apterous, 

 which is distinctly robust and characterized by a yellow blotch on the 

 back, not unlike an inverted "Y." This 

 species clusters in great colonies at the 

 tips of the young shoots. 



Nature of Work.— The leaves and 

 petioles become sticky with honey-dew 

 upon which the black soot fungus 

 grows. The entire tree may also be- 

 come very unsightly because of this. 



Distribution. — This pest occurs 

 throughout the entire State wherever 

 the food plants grow. 



Food Plants. — The common cotton- 

 wood (Popidus trichocarpa) and other 



Fig. 63. 



-The mottled cottonwood 

 plant louse, Thomasia popuUcola 

 (Thos. ). Apterous female. Greatly 

 enlarged. (Author's illustration, P. 



poplars, including Popidus fremonti, c. Jr. Ent.) 

 and willow become infested with this louse. 



Natural Enemies. — This plant louse is attacked by many natural 

 enemies, chief of which is the native ladybird, Scymnus ncbulosus Lee. 



THE MONTEREY PINE APHIS 



Essigella calif ornica (Essig) 



(Lachnus californiciis Essig) 



(Fig. 64) 



Description.— The mature aphis is noticeably long and slender, light 



green with dark markings, minute 

 red spots on the dorsum and very 

 long hind legs. The average length 

 is about 1-16 inch. 



Life History.— So far as known all 

 stages are passed on the pine trees 

 where the lice are not abundant un- 

 til the middle of summer, although 

 specimens have been taken in the 

 winter. 



Distribution.— This species occurs 

 throughout the State. 



Food Plant.— This plant louse at- 

 tacks the Monterey pine and yellow 



Fig. 64. — The Monterey pine aphis, ^mp fppdinp- on thp r>pprllp<s arnnnd 



Essigella calif omica (Essig). I mie < leeumg on xne neecues, arounu 



Winged female, nymph and apterous which it clasps its long hind leSTS for 

 female. Greatly enlarged. (Author's , 



illustration, P. C. Jr. Ent.) Support. 

 6 — 13664 



