60 



BULLETIN 903, U. S. DEPARTMENT OF AGRICULTURE. 



Some of the lower pots of the cages were filled with quartz of 

 mixed grades. This was done chiefly for the purpose of experi- 

 menting with liquid fertilizers as to the bearing of fertilizing 

 substances upon the behavior of infested vines as an adjunct to 

 similar vineyard experiments. Twelve out of 36 lower pots con- 

 tained quartz. It was found that the wandering larva? were able 

 to descend to rootlets growing in the quartz as easily as to those 

 growing in earth. On the other hand, the phylloxera? were not able 

 to exist on the larger roots in the- quartz in appreciable numbers, 

 as it appeared that they could not pass through the quartz when it 

 was packed around the root. This is similar to the condition existing 

 on very sandy soils, wherein the phylloxera? are unable to travel 

 when the sand becomes packed around the roots. 



Table XIII indicates the incubation and development of the 

 radicicoles on the roots of living vines. 



Table XIII. — Incubation and development of radieicole of the grape phylloxera 



on living vines, Walnut Creek, Calif., 1913-1915. 



FIRST GENERATION, 1913. 



Indi- 

 vidual 

 No. 



Date egg 

 deposited. 



Date egg 

 hatched. 



Incuba- 

 tion 

 period. 



Date 



insect 

 matured. 



Growing 

 period. 



Total 

 period of 

 develop- 

 ment. 



Variety of vine and 

 number of cage. 



Average 

 temper- 

 ature. 



1 



Apr. 29 

 May 28 

 ...do.... 



...do 



...do 



May 14 

 June 6 

 ...do.... 



...do 



...do 



Bays. 

 15 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 9 

 8 

 8 

 9 

 8 

 10 

 9 

 9 

 11 

 10 

 9 

 9 

 11 

 11 

 12 

 9 

 9 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 10 

 11 

 11 

 12 

 12 

 12 

 12 

 12 

 14 

 14 



June 8 

 June 25 



...do 



June 26 

 June 28 

 June 29 

 June 30 

 ...do.... 



...do 



July 5 

 Julv 8 

 July 7 

 July 9 

 July 14 



...do 



July 15 

 July 18 

 July 21 

 July 9 

 ...do.... 

 July 13 



...do 



July 15 

 July 7 

 July 8 

 July 2 

 ...do.-.. 

 ...do.... 

 July 4 

 July 6 



...do 



...do 



July 7 

 ...do.... 

 June 19 

 June 21 

 June 23 

 June 24 

 June 25 



...do 



June 27 



...do 



June 29 

 July 2 

 July 3 



Days. 

 25 

 19 

 19 

 20 

 22 

 23 

 24 

 24 

 24 

 13 

 16 

 14 

 17 

 20 

 20 

 21 

 22 

 25 

 22 

 22 

 24 

 24 

 25 

 20 

 21 

 14 

 14 

 14 

 16 

 18 

 18 

 18 

 19 

 19 

 15 

 17 

 18 

 19 

 19 

 19 

 21 

 21 

 23 

 24 

 25 



Days. 

 40 

 28 

 28 

 29 

 31 

 32 

 33 

 33 

 33 

 21 

 24 

 23 

 25 

 30 

 29 

 30 

 33 

 35 

 31 

 31 

 35 

 35 

 37 

 29 

 30 

 24 

 24 

 24 

 26 

 28 

 28 

 28 

 29 

 29 

 25 

 27 

 29 

 30 

 31 

 31 

 33 

 33 

 35 

 38 

 39 



Mission VII 



60 



2 



do 



67 



3 



4 

 5 



do 



do 



do 



67 

 67 

 67 



6 



...do.... 

 ...do 



...do 



...do 



....do 



67 



7 



do... 



67 



8 



...do 



...do 



.do.. . 



67 



9 



..do.. . 



...do 



. .do... 



67 



10 



June 14 

 ...do 



June 22 

 ...do 





69 



11 



do 



69 



12 



...do.... 

 ...do.... 

 ...do.... 

 June 15 



...do 



...do.... 

 June 16 

 June 8 



...do 



...do 



...do 



...do 



...do 



...do 



June 23 

 June 22 

 June 24 



...do.... 



...do.... 

 June 26 



...do.... 

 June 17 



...do 



June 19 



...do.... 

 June 20 

 June 17 



...do 



...do 



69 



13 



do 



69 



14 



....do 



69 



15 

 16 



do 



do 



69 

 69 



17 



do 



69 



18 



. ..do 



69 



19 





68 



20 



.do 



68 



21 



....do 



69 



22 

 23 



do 



do 



69 

 69 



24 



....do 



68 



25 



....do 



68 



26 



...do 



...do 



.do.. . 



June 18 



...do 



..do 



do 



68 



27 



....do 



68 



28 



.do 



68 



29 



...do 



...do 



....do 



68 



30 



.do.. . 



..do 



.do 



68 



31 



...do 



.do.. . 



...do 



...do 



. ..do 



68 



32 



.do 



68 



33 



...do 



...do 



....do 



68 



34 



.do... 



...do 



..do 



68 



35 



May 25 

 ..do 



June 4 

 ...do 



....do 



67 



36 



. ..do 



67 



37 



...do 



..do... 



June 5 

 ...do 



..do 



67 



38 



..do.. . 



67 



39 



...do 



...do 



...do.... 



...do 



...do 



June 6 

 ...do.... 



...do 



...do 



..do 



..do 



67 



40 

 41 



do 



. ..do 



67 



67 



42 

 43 



do 



do 



67 

 68 



44 



...do.... 

 ...do.. . 



June 8 

 ...do 



....do 



68 



45 



do.. . 



68 













