INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 73 



California the latter hibernate on the roots and may continue for at 

 least four years without reverting to the sexual forms. 



Nature of Work. — In this State the first symptoms of the presence 

 of phylloxera are the gradually dying vines in certain areas or 

 throughout the vineyard. These dying areas are usually enlarged 

 every year. An examination of the small roots will reveal small 

 bead-like swellings and perhaps some of the minute plant lice them- 

 selves, but the swellings on the roots are the most characteristic 

 injuries produced by this insect. "In the Eastern States the rough 

 wart-like galls upon the leaves are even a more noticeable work of 

 the phylloxera. 



Distribution.— "While this pest has been supposed to be limited to 

 the central portions of the State, its appearance in the north seems 

 to indicate that it occurs to some degree in most grape-growing 

 sections north, and one place south, of the Tehaehapi. 



Food Plants. — This insect feeds upon practically all varieties of 

 grapevines, but is most damaging to the European varieties. Many 

 cultivated varieties and hybrids as well as wild species are slightly 

 attacked, but not so as to greatly impair their vitality and growth. 

 These latter are known as resistant vines and are important factors 

 in the selection of roots for vines set out in phylloxera-infested dis- 

 tricts. The main source of injury is due to the attacks upon the 

 young and vigorous roots which are completely destroyed. The 

 roots of the so-called "resistant stock" do not materially suffer from 

 such attacks. 



Control.— By far the most important method of control is the use 

 of resistant root-stocks upon which are grafted the desired varieties. 

 Of course, care must be exercised in selecting stock for the various 

 varieties and expert advice obtained before making extensive selec- 

 tions or plantings. 



Direct remedies for infestations are unsatisfactory. Flooding the 

 vineyards, if the water can be held for a month, will almost exter- 

 minate the pest, if done in the winter, but such a method is impracti- 

 cable in most of the grape-growing sections of the State. 



Carbon bisulfid is an efficient remedy in sandy soil, but in such 

 places the pest is usually less abundant. 



COOLEY'S CHERMES 



Chermes cooleyi Gillette 



[Gillettea coweni (Gillette)] 40 



(Chermes cooleyi coweni Gillette) 47 



(Fig. 5 8) 



Description. — The presence of this louse is plainly indicated in the 

 spring of the year by the many small tufts of white, cottony material 

 which cover the small bodies of the individual females resting on the 

 needles of the food plants. The hibernating females or stem-mothers 

 are exceedingly small, very dark green or black with a fringe of white, 



46 Zol. Anz., XXXIV, p. 498. 



"Gillette, C. P., Proc. Acad. Nat. Sci. Phil., pp. 10-14, 1907. The description and 

 life history were taken from Professor Gillette's paper. In a recent letter he has 

 informed the writer that he considers all of the above only forms of the same species. 



