20 



SECOND REPORT ON ECONOMIC BIOLOGY. 



laboratory bench. This has an oiled teak top, and the surface is, of 

 course, considerably rougher than either the paper or glass. 



The procedure adopted was similar to that recorded above, and 

 the results obtained are interesting as the surface more nearly 

 resembled the actual natural conditions than in the case of either the 

 glass or the paper. 



RATE OF TRAVEL ON TEAK BOARDS. 



* Specimens died. 



In another case I placed some 60 to 70 newly-hatched Currant 

 Scale on a sheet of white cardboard and exposed them to a tempera- 

 ture of 100 to 102 F. ; they slowly dispersed over the board, and at 

 the end of three and a half hours were fairly well scattered over an 

 area of about two square feet. I then turned the board over. 

 Examined four hours later nineteen of the scales had made their way 

 on to the upper surface ; sixteen hours later, quite fifty were on the 

 upper surface exposed to a temperature of 102, a few had fallen off 

 the under surface and a few .were dead. 



Other experiments similar to those recorded by Mr. Quayle were 

 tried, with very similar results, with this exception that I was unable 

 to get a temperature any higher than 107 F. 



Mr. Quayle 1 states that young examples of the Black Scale 

 (Saissetia oleae, Bern.) died at a temperature of 84 F. " Experi- 

 ments," he states, " relating to the effect of high temperature on 



1 Journ. Econ. Entom., 1911, vol. iv, p. 305. 



