INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



85 



This has just recently been proven true for California also. Mr. Geo. P. 

 Weldon has received specimens of the common reed from Lassen County 

 in August badly infested 

 with this louse. There are 

 several broods a year. 



Nature of Work.— The 

 plant lice settle in great 

 numbers upon the under- 

 sides of the leaves, often 

 entirely hiding the sur- 

 face and causing them to 

 curl and droop and thus 

 greatly reducing the 

 vitality of the trees. Much 

 honey-dew is also secreted, 

 causing the growth of 

 black smut. 



Distribution. — This 

 aphid is specially abun- 

 dant in the central and 

 northern parts of the 

 State, where prune raising 

 is most important. It has 

 never been reported from 

 the southern part of the 

 State, though it may occur 

 there unobserved. 



Food Plants. — The 

 plum and prune are the 

 normal hosts of this louse 

 in California. The com- 

 mon reed (Phragmites 

 vulgaris) is the alternate 

 summer host wherever 

 this plant louse is known 

 to occur. 



Control. — Fortunately 

 the attacks of the mealy plum plant louse are spasmodic and are of 

 short duration, seldom requiring control measures. However, it is 

 sometimes advisable to use remedies and tobacco decoction, and other 

 sprays recommended for the green apple aphis should be applied in 

 such cases. 



Natural Enemies. — The larva? of the green lacewing (Chrysopa cali- 

 forniea), of ladybird beetles and of syrphid flies play a very important 

 part in keeping down the numbers of this insect. 



Fig. 68. — The mealy plum plant louse, Hyalopterus 

 arundinis (Fab.), on the underside of a prune leaf. 

 Enlarged twice. (Author's illustration, Mo. Bui. Cal. 

 Hort. Com.) 



