120 BULLETIN 903, U. S. DEPARTMENT OF AGEICULTTJRE. 



swimming around in circles, but those at the bottom remained almost 

 motionless unless disturbed. 



To sum up, it appears: (1) That eggs of radicicoles hatch readily 

 in water, floating and sunken ; (2) that the newly hatched larvae 

 may live for more than a week submerged, or on the surface film; 

 (3) that these larvae are capable, at least after four days of exposure 

 to water, of fixing upon roots and developing in a normal manner. 

 Further proof of the ability of young phylloxeras to live submerged 

 occurred in an observation made from September to November, 

 1914. A Riparia cutting had been placed in a glass vial in the 

 laboratory. Immediately a callus formed, and many rootlets grew 

 around the inside of the vial. On September 15, 20 eggs of radici- 

 coles were floated on the water surface. None of the resultant larva? 

 persisting, more eggs were floated October 10. October 12 the water 

 had evaporated, and four days later two young larvae had settled. 

 These had hatched after the water evaporated. About 1 inch of 

 water was then poured into the vial to cover completely all the root- 

 lets and the two phylloxeras. October 22, three larvae were observed 

 under water, one of which had been fixed since October 16. October 

 27, there were visible under water, besides the original larvae of 

 the 16th, six additional larvae, five of which were settled. October 

 30 all seven observed on October 27 had settled and an eighth was 

 visible moving over the rootlets. A small tuberosity had been set 

 up by one of the phylloxeras. All the unhatched eggs had died. It 

 was noted that when the insects were exposed to sunlight they moved 

 their appendages actively. November 2, three settled larvae were 

 visible. These included the individual on the tuberosity and the 

 one which had settled October 16. All others were dead. November 

 10 the only survivors were the original settler and the individual 

 on the tuberosity. Shortly after November 20 all disappeared. 

 Thus one individual, destined apparently to hibernate, persisted more 

 than a month fixed on a root under water, and several others lived 

 under water from 3 to 14 days. 



There also exists the possibility of infestation by seepage. On 

 vineyards of porous soils young larvae on the surface may be drawn 

 into the soil in time of a storm or irrigation. Also on steep hillside 

 vineyards in the springtime, when heavy rains may fall or when a 

 rise and fall in the " water table " may occur, a seepage infestation 

 may take place. Any artificial irrigation during the months June 

 to October invites the spread of phylloxeras because in this period 

 phylloxeras occur above the surface of the soil or are active on surface 

 rootlets. 



CUTTINGS AND ROOTED VINES. 



In European countries where a small percentage of the winter 

 eggs are deposited under the bark of yearling wood there is a slight 



