BIOLOGY OF TOBACCO MOTH AND ITS CONTROL 



15 



a choice, moths will select for oviposition those grades of tobacco 

 high in sugar. Bovingdon (4- pp. 37-1^) conducted food-selection 

 experiments which showed that tobacco moths preferred to oviposit 

 on flue-cured tobacco. This investigator used dark-fired tobacco in 

 comparative tests and concluded that the toxic substances on leaves 

 of this type, such as formaldehyde, pyroligineous acid, and methyl 

 alcohol, were probably responsible for the choice of the other type. 

 The effect of the quality and grade of cured tobacco on the growth 

 and reproduction of the tobacco moth is a problem which should 

 receive further study. 



80 



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JUNE JULY AUG. SEPT. OCT NOV. DEC. 



Figure 10. — The relative humidity and mean temperature in the unheated laboratory at 

 Richmond, Va., averaged for each semimonthly period of 1932 and 1933. 



TEMPERATURE 



Since a more rapid growth of the insects occurred in 1933 than in 

 1932. and this was apparently due to higher average temperatures, it 

 is considered worth while here to discuss the temperatures that pre- 

 vailed in those years. In figure 10 are given the mean temperatures 

 and average relative humidities for semimonthly periods in the labora- 

 tory during 1932 and 1933. 



The temperature during the first 6 months of 1933 was consider- 

 ably higher than in 1932. This higher temperature, however, failed 

 to affect materially the rate of emergence of spring-brood moths. 



