THE TERRAPIN SCALE. 83 



It requires from 1| to 2\ gallons of this emulsion thoroughly to 

 spray a vigorous 12-year-old tree. The average tree of this age 

 requires about 2 gallons, while a 2-year-old tree requires from a pint 

 to a quart. It appears that from these figures the spray material 

 will cost from 1 cent to 8 cents per tree. 



A single application of this spray, if carefully made, will control 

 the terrapin scale. It has been found that the best way of preparing 

 this spray is by mixing 5 gallons of raw linseed oil and 3 gallons of 

 gasoline and then adding 2 pounds of soap dissolved in 4 gallons of 

 hot water. The whole is churned for 5 minutes through a spray 

 pump, then diluted to double its volume and churned again for 1 

 minute, after which it should be diluted to 100 gallons, when it is 

 ready to use. 



MIXED OILS. 



Two experiments were performed in 1913 with emulsions of mixed 

 oils. These emulsions were made and applied in exactly the same 

 way as the linseed-oil emulsions. 



Table XLII shows the chief details, and the results for the mixed- 

 oil emulsions. These experiments, when compared with experi- 

 ments 3 and 4 of Table XLI, show that these mixed oils were less 

 efficient than raw linseed oil and that there is no advantage in mixing 

 them. 



NICOTINE. 



Eight experiments were made with nicotine compounds. These 

 sprays were applied partly with a barrel sprayer and partly with a 

 power sprayer, but the same set of disk nozzles was used in all cases. 

 The chief details and the results of these experiments are recorded 

 in Table XLIII. 



When reference is made to nicotine sulphate, the commercial article 

 containing 40 per cent of nicotine is intended; likewise references to 

 tobacco extract refer to preparations containing 2.7 per cent of 

 nicotine, or its equivalent. 



Experiments 5 and 6 of Table XLIV and experiments 5, 6, 7, and 8 

 of Table XLV are to be considered in connection with Table XLIII. 

 Of these 14 experiments, 5 were directed against the hibernating 

 scales (4 of these in the spring and 1 in the fall) ; 5 against the leaf- 

 attached larvae, 2 against the females while making the twigward 

 migration, and 2 against the young females while making their 

 maximum growth. These experiments were all negative and showed 

 that nicotine is ineffective against the terrapin scale. 



COATING SPRAYS. 



A number of experiments were performed in 1912 with coating 

 sprays, to determine the feasibility of smothering the scale. The 

 chief details and the results of these experiments are recorded in 



