44 THE MONTHLY BULLETIN. 



thorax and blaekish-ln-own alidomeii. In the mature winged form the 

 abdomen is greenish. 



Life History. — The insects appear with the first healthy growing- 

 shoots, which they attack vigorously. They increase rapidly and 

 often do great damage. All stages are to be found throughout the 

 summer months. 



Distribution. — Tliroughout the State, especially in the Sacramento 

 Valley. 



Food Plant. — The pear. 



Control. — Same as for plant lice {Aplddidce), consisting of soap and 

 emulsion spra.ys. 



Natural Enemies. — The two-spotted ladybird beetle (Adalia hipunc- 

 tata Linn.) and the green lacewing {Clirysopa calif ornica Coq.) feed 

 upon the eggs and larvas of the pear psylla. 



APHIDIDv^ (Family). 



PLANT LICE. 



The members of this family comprise one of the most important 

 groups of destructive insects known. Every one is familiar with the 

 soft-bodied winged and wingless lice which gather so a])undantly upon 

 all sorts of plants. The proboscis appears to rise in the middle of the 

 sternum, the legs being rather long and slender; the wings when pres- 

 ent are membranous and with few veins. Many of the females of this 

 family have the power of producing living young without sexual inter- 

 course, though true sexual forms usually appear sometime during the 

 life cycle. Winged or migratory forms also appear. Some species live 

 almost entirely underground while others are aerial in habits. As this 

 family plays such an important part in the role of insect pests, we are 

 including a large number of the most common species. 



The life history of the green apple aphis {Aphis pomi De Geer) is 

 given as an example on page 67. 



METHODS OF CONTROL. 



Plant lice are more subject to the attaclvs of other insects than per- 

 haps any other one group of insects, but several species are by no means 

 held in subjection by these natural enemies. In considering methods of 

 control, then, we should take into account the natural as well as the 

 artificial. 



Natural Enemies. 



Three families of insects are recognized as effectual predaceous 

 enemies of plant lice. They are, Syrphidce, Coccinellidce and CJiry- 

 sopidce. 



SyrpJtidce. The larva of th(^ syrphid flies are legless, worm-like 

 animals, which are usually found among the plant lice upon which they 



