ANIMALS INJURIOUS TO FRUIT TREES. 21 



young black scales showed that it is an important factor in the causes 

 of death. Several hundred young black scales were liberated on 

 white cardboard in the sun with a temperature of 94 to 100 ; at the 

 end of two hours they were unharmed by the heat. A similar experi- 

 ment is recorded with a temperature of 106 to no. At 106 the 

 scales were lively, but as the temperatures increased, they moved 

 more slowly, and at 110 almost all movement ceased, although a two 

 hours' exposure did not kill them. 



Several hundred just emerged black scales liberated on soil with 

 a temperature of 108 to 110 were active for about one hour, but at 

 the end of that period some were dead, and at the end of one and a 

 half hours nearly all had been killed. A check lot in the shade were 

 not affected. A large number of young placed upon a board with a 

 temperature of 180, all died in five minutes. Scales exposed in sun 

 on soil w r hen temperature was 119 to 122 died within fifteen minutes. 

 Under similar conditions, with the temperature of 130, death resulted 

 in five minutes. A check lot in the shade were not affected." 



The distances travelled by P. vitis v. ribcsiae are considerably 

 shorter than those reported by Mr. Quayle, e.g., on smooth paper; 

 in two hours the Black Scale (Saissetia oleae, Bern.), at a temperature 

 f 73-5 F., travelled a distance of 71.5 inches; at 80, 76.5 inches; 

 at 83, 123.33 inches; and at 90, 151.33 inches. The Red Scale 

 (Chrysomphalus aurantii, Mask.) at 66 travelled 31.12 inches, and 

 at 91, in inches. The Purple Scale (Lepidosaplies beckii, Newm.) 

 at 62, 19.16 inches; at 68, 32.87 inches; and at 89, in inches. 



Temperature undoubtedly plays a very important part in the rate 

 and distance of travel. 



On looking through a number of the leading works on the 

 Coccidae I have been unable to find any reference as to the length of 

 time the larvae will live when separated from their food plant. As 

 the subject is one of considerable economic importance, the following 

 observations may prove useful and interesting. 



On July 6th I received a cutting from a Black Currant bush 

 badly attacked with the White Woolly Currant Scale (P-idvinaria 

 vitis var. ribesiae, Sign.). On the afternoon of the same day large 

 numbers of the orange-red coloured larvae were noticed dispersing 

 over the laboratory bench, some two hundred of which invaded a 

 cardboard box. 



