THE TERRAPIN SCALE. 89 



Nicotine. 



In group 6 the efficiency of nicotine was tested in 14 experiments. 

 Both the commercial sulphate and the aqueous solution were tested. 

 This substance proved inefficient in all cases. 



Coating Sprays. 



In group 7 various coating sprays were tested. Twenty experi- 

 ments were made. They were intended for the control of both the 

 sooty fungus and the terrapin scale, but were ineffective against the 

 "soot" in all cases where the insect was not killed. 



From these experiments it is evident that the period in the life 

 history of this insect when it can be most readily controlled by a coat- 

 ing spray is during the leafward migration. It is also evident that sul- 

 phur is the efficient component in the coating sprays, and that the 

 ordinary self-boiled lime-sulphur lacked the spreading and adhesive 

 properties necessary to make it an efficient coating spray. The modi- 

 fied formula given under " Recommendations " (second formula, 

 below) was accordingly devised. 



RECOMMENDATIONS FOR CONTROL. 



Spray in the spring before the buds burst, with the following 

 emulsion (see page 82): 



Raw linseed oil 5 gallons. 



Gasoline 3 gallons. 



Soap 2 pounds. 



Water 92 gallons. 



If the foregoing formula is not used, spray with proprietary miscible 

 oils, containing not less than 75 per cent mineral oil, at the rate of 

 1 part to 16 to 20 parts of water. Applications of this formula should 

 likewise be made in the spring during the period between the swelling 

 and the opening of the buds. (See pp. 68-73.) 



To protect a crop after the trees are in foliage, spray just before 

 the leafward migration (see pp. 19-24) with the following formula 

 (p. 85): 



Flour (in paste) 10 pounds. 



Stone lime 15 pounds. 



Sulphur 20 pounds. 



Water to make 50 gallons. 



This should be applied at the time the young appear in the brood 

 chambers, but before they have emerged. This time can be best 

 determined by making a daily examination of infested twigs. Since 

 the young are not destroyed after they have attached, only one 

 thorough application is advisable. This treatment, owing to the 

 limited time for its application, is not as practicable as the dormant 

 sprayings and should be used only in emergencies. This spray does 

 not seriously coat the fruit. 



