40 



DECIDUOUS FRUIT INSECTS "AND INSECTICIDES. 



In Plat II of Table XXXVI, recording the 1909 experiments at 

 Concord, worms were not so prevalent, the fruit on the unsprayed 

 plat being only 53.05 per cent wormy and only about 31 per cent of 

 the fruit dropping from the trees. (See Table XXXVIII.) This plat 

 shows a much higher percentage (13.869 per cent) of the pears 

 wormy at the side and stem. Also, if we examine Plat V of Table 

 XXXIV, recording the 1910 experiments at Walnut Creek, we find a 

 higher percentage of pears wormy at the side and stem, namely, 

 11.699 per cent as against 8.198 per cent in the check block. Plat V 

 received no treatment for the first-brood worms, but was sprayed 

 once on July 4 just before the second-brood worms began to enter 

 the fruit. The surface of the fruit was fairly well covered, yet the 

 percentage of fruit wormy at the side and stem was greater than 

 was that of the unsprayed block. In this case it will be seen 

 (Tables XLIV and XLV) that there was more fruit on the trees at 

 picking time in Plat V than on the trees of the check plat. Also 

 there were correspondingly more windfalls from the trees in the check 

 plat than from the trees in Plat V. 



All of the plats receiving the first spraying (soon after falling of 

 petals) show a comparatively light infestation at the calyx, and those 

 receiving the two early sprayings have very few pears wormy at the 

 calyx. (See Plats I, II, III, and VII, Table XXXIV.) Those plats 

 on which this first spraying was omitted have a greater percentage of 

 pears wormy at calyx, although they received one thorough spraying 

 just before the first-brood worms began to enter the fruit, which was 

 some four weeks after the petals had fallen. (See Plats IV and VIII, 

 Table XXXIV.) 



Table XXXIV. — Degree of infestation and relative infestation at different places of 

 entrance by codling-moth larvae. Plats I to VIII, inclusive, Walnut Creek, Cal., 1910. 



Plat. 



Total 

 number, 

 of pears. 



Total 

 number 

 of wormy 



pears. 



Degree of infestation. 



Relative infestation at differ- 

 ent places of entrance. 



Total per 

 cent of 

 wormy 

 pears. 



Total per 



cent of 



pears 



wormy 



at calyx. 



Total per 

 cent of 



pears 

 wormy at 

 side and 



stem. 



Total 

 number 

 of worms 

 (100 per 



cent). 



Percent- 

 age of 

 worms 

 entering 

 at calyx. 



Percent- 

 age of 

 worms 



entering 

 at side 



and stem. 



Plat I, sprayed Apr. 



9, May 2, July 14... 

 Plat II, sprayed Apr. 



9 and May 2 



Plat III, sprayed 



Apr. 9 and July 4 . . . 

 Plat IV, sprayed May 



2 and July 4 



Plat V, spraved July 



4 



Plat VI, unsprayed 



check 



Plat VII, sprayed 



Apr. 9 



Plat VIII, sprayed 



May 2 



3,126 

 4,415 

 2,477 

 4,096 

 2,248 

 2,427 

 2,128 

 2,811 



126 

 472 

 506 

 922 

 1,976 

 2,279 

 693 

 857 



4.03 

 10.69 

 20.43 

 22.51 

 87.90 

 93.90 

 32.57 

 30.49 



0.223 

 .747 



5.611 

 11. 621 

 76. 201 

 85.702 



9.020 

 14. 695 



3.803 

 9.943 

 14. 816 

 10.888 

 11. 699 

 8.198 

 23. 550 

 15. 795 



126 

 472 

 506 

 922 

 1,976 

 2,279 

 693 

 857 



5.56 

 6.79 

 27.47 

 51.63 

 86.18 

 91.27 

 27.71 

 48.19 



94.44 

 93.21 

 72.53 

 48.37 

 13.82 

 8.73 

 72.29 

 51.81 



