TWENTY-NINTH FRUIT-GROWERS' CONVENTION. 171 



The fact that both the lead and lime arsenicals can be made at home 

 is a point in their favor in the minds of some growers, inasmuch as the 

 danger from impurities and neglectful methods of manufacture is 

 removed when they are used. Our experiments this season certainly 

 show their great value, and they are deserving of extensive use in this 

 State in the future. The results of this season's work indicate that a 

 very large degree of control can be obtained, but the seasonal conditions 

 in the development of the worms must be studied to obtain this success. 

 There are times in the life history of the moth Avhen the presence of the 

 poison on the fruit will be very effective in protecting the crop, while at 

 other times the need of protection would not be so great. 



Our studies during the season just past indicate two times of maxi- 

 mum appearance of the moths in the Pajaro Valley, and the most 

 effective sprays are evidently those applied at these times. These times 

 of maximum development may be roughly stated as occurring in the 

 late spring or early summer and in the late summer or early fall. We 

 know from our studies this season that, owing to certain climatic con- 

 ditions, a portion of the region under discussion may be classed as 

 immune against the codling-moth. Other parts of the territory suffer 

 exceedingly from this pest, and various grades of susceptibility are 

 found between these two extremes. Where the condition of immunity 

 exists, of course no spraying operations are necessary. In all other 

 cases studies must be carried on in each individual orchard, or at least 

 in each local group of orchards, to determine the time for spraying and 

 the number of applications to be made. As for the spring spraying for 

 placing the poison in the blossom cup, this may, under certain condi- 

 tions, as has been pointed out in the previous paper, be omitted. How 

 widely this policy is safe can only be known after careful experiments 

 have determined the point for each locality. 



The time to spray for the spring brood of worms, where this brood 

 causes a considerable loss, can be readily determined by the breeding- 

 cage method. This consists in placing a number of the hibernating 

 worms in glass jars and covering the mouths of the jars with cheese- 

 cloth. These may be taken in their pupa cases from old boxes, bands, 

 or other likely places during the winter. These jars should then be put 

 out in the orchard in such situations that the sun will not shine on 

 them, nor water leak into them, and yet where the pupae in them will 

 be subject to all the temperature changes of the season. A careful 

 watch of these improvised breeding cages should be kept, and when 

 moths begin to appear in them in numbers spraying should begin about a 

 week thereafter, and this spraying should be repeated in about three 

 weeks. It will be advisable to examine the jars regularly once a week and 

 to remove the living moths from the jars each time, so that the count of 

 appearances may not become confused. 



