CONTROL OF CODLING MOTH IN COLORADO. 15 



Plat VI, which was sprayed six times ^vith arsenate of lead and 

 fish-oil soap, yielded 78.06 per cent of apples free from worms, which 

 was the highest percentage of uninfested fruit in the orchard. Also 

 the average number of worms for all apples was as low in this plat 

 as in any other. The percentage of all apples free from worms and 

 stings in plat Vi was 46.22, which was not as high as that obtaining in 

 plats IX (46.44 per cent), V (47.84 per cent), and IV (49.82 per cent). 

 Plat IX produced the next best results, 76.53 per cent of all the fruit 

 being free from worms as a result of seven applications of arsenate of 

 lead; plat V, with five treatments supplemented with the codling-moth 

 trap, yielded 72.29 per cent of uninfested fruit; plat IV, 72.05 per 

 cent, with six applications of arsenate of lead and nicotine sulphate. 

 Two other plats, I and VIII, produced 70.99 and 73.49 per cent of 

 worm-free fruit, respectively; the former being sprayed six times with 

 arsenate of lead, supplemented with the codling-moth trap, and the 

 latter having only five applications of arsenate of lead. Plat II, 

 which received six applications of arsenate of lead, yielded but 62.10 

 per cent of worm-free fruit, and but 27.04 per cent of fruit free from 

 worms and stings. Apparentl}^ the infestation in this plat was some- 

 what heavier than that which prevailed in some of the other plats. 

 Plat III was treated six times with nicotine sulphate, which resulted 

 in but 37.97 per cent of fruit free from worms. The percentage of this 

 fruit free from stings was relatively high (88.62 per cent), a condition 

 which would naturally be expected, owing to the fact that the majority 

 of the larvae that attacked the fruit were able to enter it without being 

 killed by the spray. Attention is called to the fact that in this plat 

 (plat III) 18.07 per cent of all the worms infesting the apples entered 

 by way of the calyx end and that 22.39 per cent of the wormy apples 

 were infested at the cajyx. In plat VII arsenate of lime was used with 

 unsatisfactory results, there being 36.51 per cent of worm-free apples 

 and only 20.33 per cent of the fruit free from worms and stings. 

 Plat X was sprayed at the same time as the plats that had six treat- 

 ments, except that the calyx application was omitted, thus making 

 a total of five treatments. The percentage of worm-free fruit was 

 46.33, and the percentage of all apples free from worms and stings was 

 25.36. It is worthy of note that the percentage of worms entering 

 the calyx was high (29.83 per cent), ai^d that 37.42 per cent of the 

 wormy apples were infested at the calyx. 



Plats XI, XII, and XIII were dusted six times with mixtures con- 

 taining 20, 15, and 10 per cent of arsenate of lead, respectively. The 

 results of these treatments indicate quite conclusively that dusting is 

 unsatisfactory for the control of the codling motli in the Grnnd 

 Valley. With as much as a 20 per cent lead arsenate mixture only 

 40.75 per cent of the fruit was free from worms; with a 15 per cent 

 lead arsenate mixture there was 34.58 per cent of worm-free fruit; 



