June, '21] 



HEADLEE: BEAN WEEVIL AND MOISTURE 



267 



100% atmospheric moisture seemed to be considerably delayed, pos- 

 sibly by the action of the fungi. The data from these sets of experi- 

 ments, as those derived, from previous ones, indicate that the optimtun 

 atmospheric moisture for the bean weevil lies somewhere between 80 

 and 89%, and is located in that percentum which is just far enough 

 below 89 to prevent the development of injurious fungi. 



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I , :i mill mi LI 



FIG. 5 Chart showing effect of atmospheric moisture in the development o£ the 



Bean Weevil. 



As is shown by the cun^e based on the length of period from egg to 

 pupa, the value of 1% increases in atmospheric moisture at any point 

 between 7.1% and 80% is approximately two-hundredths of a day. 

 Of course, there is considerable variation in this evaluation of the 1% in- 

 crease, but the variation is such as to indicate that that figure is not 

 very far from the facts. The variation is thought to be due in all prob- 

 ability to the direct and possibly to the indirect effect of certain of 

 the salts which seemed, in some cases, to have a retarding, and in oth- 

 er cases to have an accelerating action. These variations as shown 

 in the curve representing the period from egg to pupa became much 

 more pronounced in the curve representing the period from egg to a- 

 dult. As yet the writer has had no opportunity to evaluate this fac- 

 tor, and consequently has not been able to smooth the curves. The 

 curve representing the period from egg to adult cannot be considered 

 as representing in a satisfactory'- manner the effect of the different per- 

 centages of atmospheric moisture until it has been smoothed in that way. 

 Nevertheless, the writer beHeves that it is fair to assimie that the curve 

 representing the period from the egg to pupa is already sufficiently 



