August, 17] ESSIG: TOMATO AND LAUREL PSYLLIDS 443 



During the winter months when the adult stage only persists, the 

 plants may be removed to a fumigating house or tent and fumigated 

 and if immediately removed to a safe distance from all other points 

 they may be kept free from reinfestation and shipped elsewhere if 

 they remain clean after a few months' time. 



Spraying with miscible oils and oil emulsions readily kills all stages 

 if repeatedly and thoroughly applied. The manufactured grades of 

 miscible oils and kerosene emulsion, crude oil emulsion, and crude 

 carbolic acid emulsion may be used.^ 



Hand-picking has been resorted to in one nursery, but the results 

 have not been satisfactory because of immediate reinfestation. 



To get satisfactory results all infested plants must be segregated 

 and removed from other plants to a perfectly clear place and the 

 treatment applied to all as fast as possible and in a definite direction, 

 beginning at one side or end. If the area is so large that it will require 

 more than a few hours to make the treatment, the plants must be 

 removed elsewhere as fast as treated or else they will become rein- 

 fested with the adults before the last ones are reached. This has been 

 the fault of most of the work done so far. 



Summary 



1. Of some fifty described species only two psyllids may be consid- 

 ered of economic importance in California. They are the tomato 

 psyllid, a native species and the laurel psyllid, imported from Europe. 



2. The tomato psyllid is generally distributed throughout the state, 

 and, while it prefers solanaceous food plants, also infests others. 



3. The tomato psyllid may be controlled by spraying, but is only 

 occasionally serious enough as a pest to warrant a treatment. 



4. The laurel psyllid is a serious enemy of the laurel or sweet bay 

 tree, causing disfigurations of the foliage, smutting and generally 

 stunting the plants. 



5. The distribution of the laurel psyllid is limited to a few localities 

 in the San Francisco Bay region. 



6. When the laurel psyllid is present it is necessary to employ con- 

 trol measures which consist in spraying or fumigation. 



7. The laurel psyllid is of sufficient importance to warrant a con- 



■ For the f ormulge and methods of preparing and using the above sprays see : 

 Woodworth, C. W., Circ. No. 128, Cal. Agrcl. Exp. Sta., pp. 3-5, April, 1915 (This 

 circular may be had by applying to the Director of the Agricultural Experiment Sta- 

 tion, Berkeley, Cal.). 



Essig, E. O., Inj. Ben. Ins. Cal, 2d ed., Cal. Hort. Com., pp. 465-480, May, 1915 

 (This publication may be secured from the State Commissioner of Horticulture, 

 Sacramento, Cal.). 



