34 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 10 



moisture, the period ranging from 20 days in 100 per cent to 27 in 

 44.1 per cent in the first brood and from 38 in 100 per cent to 41 in 39.9 

 per cent in the second brood. It seems clear that a reduction of mois- 

 ture to 26 per cent or below absolutely prevents reproduction. It seems 

 also that in 100 per cent fungi may develop to such an extent that both 

 weevil and beans are destroyed. 



The great reduction in progeny which accompanied the reduction in 

 atmospheric moisture led to an investigation of the cause. Thinking 

 that the reduction might be the result of reduced fecundity a study of 

 that phase was undertaken. 



Table Showing the Effect op Different Degrees of Atmospheric Moisture on the Number of Eggs Laid 



While reduction in atmospheric moisture reduces the number of 

 eggs produced by the average female, that reduction is certainly not 

 sufficiently large to explain the observed reduction in progeny. 



Accordingly attention was directed towards the egg stage. Eggs 

 were subjected' to two moistures 100 per cent and 23.6 per cent. They 

 hatched in both but required an average of six days in the former and 

 four in the latter. An examination seven days after the last egg 

 hatched showed many of the beans in 100 per cent penetrated by the 

 larvae and a complete absence of penetrations among the beans under 

 23.6 per cent. This seems to show that the absolute prevention of 

 progeny in 23.6 per cent is due to the destruction of the larvae before 

 they can penetrate the beans, and it seems not unlikely that the great 

 reduction in progeny which accompanies reduced atmospheric humid- 

 ity may be due to the same cause, although the effect upon the larvae 

 yet remains to be investigated. 



It thus appears that the speed of metabolism in the pupae of both 

 the bean weevil and the Angoumois grain moth varies inversely with 

 the atmospheric humidity; that in the adult of the former it varies 

 with while in the adult of the latter it varies inversely as the humidity; 

 that in the egg stage the speed of metabolism varies inversely with 

 the humidity; that in the larvae it varies with the humidity; that in the 

 life cycle as a whole the speed varies with the humidity. 



The bean weevil and the Angoumois grain moth offer many of the 

 variations in response of speed of metabolism to atmospheric moisture 



