6 



FARMERS BULLETIN 843. 



nuts in the same manner as those of the first generation, but 

 usually the injury to the nut crop by these larvae is not so great. 



Most of the moths of the third generation appear during the first 

 three weeks in August. The larvae from this generation do little 

 or no damage to the nuts, which usually are beginning to harden at 

 this time, and they seem to prefer to feed in the petioles or tender 

 shoots. The winter is passed as immature larvae in cocoons or hiber- 

 nacula, which are formed around the -buds. In rearing cages it 

 was observed that larvae which hatched from eggs laid by third- 

 brood moths usually fed very little before constructing winter cases 

 around the buds. It was noticed, however, that a very few larvas 

 fed extensively and transformed to pupae, from which moths emerged 

 during the last part of September, thus indicating a fourth generation. 

 But observations in pecan orchards failed to show any indications of 

 a fourth generation. 



CONTROL MEASURES. 



The pecan nut case-bearer is already an established pest in certain 

 important pecan-growing sections, and because of its increasing de- 

 structiveness certain experiments have been conducted for the deter- 

 mination of positive means of control. During the seasons of 1915 

 and 1916 series of spraying experiments were conducted in a pecan 

 orchard at Monticello, Fla. All sprayed plats were treated with 1 

 pound of powdered arsenate of lead plus 3 pounds of slaked stone 

 lime to each 50 gallons of water. In all cases the material was 

 applied with a well-equipped gasoline-power outfit, and a pressure 

 varying from 150 to 200 pounds was maintained. 



The results of spraying experiments for 1915 are shown in Table 1. 



TABLE 1. Spraying experiments against the pecan nut case-bearer, Monticello, Fla., 1915. 



It will be seen that Plat I, which received three applications, gave 

 78.98 per cent of sound nuts, and showed a benefit of 19.49 per cent 

 over the check or unsprayed plat, which had only 59.49 per cent of 

 sound nuts. Plat II, which received only two applications, yielded 

 a somewhat greater percentage of sound nuts, while Plat III, 

 which had only one application, yielded 74.23 per cent of sound nuts. 

 The benefit for each plat over the check plat is shown in percentages 

 as follows: Plat I, 19.49; Plat II, 21.19; and Plat III, 14.74. It is 

 worthy of mention that out of the 40.51 per cent of infested nuts on 



