86 THE MONTHIiY BULLETIN. 



Distribution. — Throughout the entire ^tate. 



Food Plants. — Carrots, parsnips, celery, willows, ineludinu' KSalix 

 anna, >S'. luckla, 8. nigra, S. caprea, S. hahijlonica, »S'. alha, and S. 

 amygdaloides, Pimpinella magna, P. saxifraga, Erysimum vulgare, 

 Archangclica atropurpurea, Zizia anrca, Cicxita virosa, Hcracleum 

 spliondyJunn, J^]gnpodium podagraria, ('han-ophyllum tcmuJiim, Ange- 

 lica sylvrstris. 



Natural Enemies. — Especially preyed upon hy the larvae -of syrphid 



flies. 



THE MEALY PLUM LOUSE. 



J/ i/alopfcrns (iruudiitis Fab. 



General Appearance. — The adult lice are long and slender, light 

 green with three dariver longitudinal stripes on the back and covered 

 Avith a white powder from whence it gets its name. It usually' occurs 

 in large colonies on the under sides of plum and prune leaves, causing 

 them to turn yellow and drop hut not to curl. 



Life History. — The first broods hatch in the spring from the black 

 shining eggs deposited upon the twigs of the trees the previous fall 

 by the sexual females. These lice settle upon the under side of the 

 first leaves and bring forth young which soon mature and produce 

 others. During the summer in July and August the lice, most of 

 which have accpiired wings by this time, leave the trees and feed upon 

 grasses ; the fall migrants returning to the trees to give birth to the 

 true sexual winged males and wingless females, which mate — the 

 females laying the over-wintering eggs. 



Distribution. — Especially al)undant in the central part of the State 

 in the fSacramento and San Joaquin valleys, as well as along the coast 

 and in the Sierra foothills. 



Food Plants. — The only fruit trees attacked appear to be the prune, 

 apricot and plum. The common reed grass {Phragmites vulgaris) is 

 also infested. 



« 



THE BLACK CITRUS LOUSE. 



Toxoptcra innantiw Koch. 

 (Fig. 68.) 



General Appearance. — A small dull black louse, scarcely over 1.5 

 mm. in length. The apterous forms often appear brown, while the 

 young are a decided reddish-brown to black. Some of the adults are 

 shim' black and have been mistaken for the black peach aphis {Aphis 

 persica'-uiger) . It is easy to distinguish the winged individuals of 

 this species by the very dark and prominent stigma and the single 

 branching of the third discoidal vein. 



