THE TERRAPIN SCALE. 85 



both against the scale and the sooty molds. They also indicate that 

 the other substances tested are ineffective against the terrapin 

 scale. 



The experiments with coating sprays performed in 1912 were fail- 

 ures, so far as controlling the terrapin scale was concerned, but they 

 were valuable in showing that sulphur was the active component of 

 self -boiled lime-sulphur and that its efficiency could be improved 

 by increasing its spreading and sticking powers. It was evident also 

 that sulphur was ineffective against the mature females. 



COATING SPRAYS WITH FLOUR ADDED. 



In 1913 experiments were made to perfect a coating spray by adding 

 a spreader and sticker to self-boiled lime-sulphur and by increasing 

 the sulphur content. The chief details and the results of these ex- 

 periments are recorded in Table XLV. 



In these experiments the flour was first made into a thin batter 

 with cold water and then cooked to form a paste. The other ingre- 

 dients were combined exactly as in making self -boiled lime-sulphur, 

 after which the flour paste was added. 



In the first four experiments the same spray was used. Experi- 

 ment 1 was directed against the larvae during the leafward migration 

 and was very successful. Experiment 2 was directed both against 

 leafward migrants and against the larvae upon the leaves. It shows 

 high efficiency, which is, however, entirely due to the first spraying, 

 as is shown by the negative results in experiment 3. 



Experiments 5, 6, 7, and 8 were performed with the same formula 

 used in the preceding experiments, except that 1 pint of 40 per cent 

 nicotine sulphate was added. The results from these experiments 

 show that the nicotine adds nothing to the efficiency of the spray. 



Experiment 9 was made with flour paste and shows that flour 

 acts only as a spreader and adhesive and not as a killing agent. 



Experiment 10 was made with modified self-boiled lime-sulphur 

 to which flour paste was added, and was directed against the larvae 

 after they were well established upon the leaves. The spray was 

 ineffective, as were all other applications made against the leaf- 

 attached larvae. 



From these experiments it appears that the terrapin scale can be 

 controlled by a coating spray applied against the larvae during the 

 leafward migration and that these sprays are inefficient at other 

 times. Coating sprays are more difficult to apply than the oil sprays 

 and require a first-class sprayer with a powerful agitator and plenty 

 of pressure. Coarse-angle nozzles should be used and the underside 

 of the leaves should be thoroughly drenched, and the spray must be 

 applied just before the young emerge. The time for applying this 

 spray, which is immediately after the appearance of young under the 



