178 
Journal of Agricultural Research 
Vol. XXXI, No. 2 
-•c. 
-°c. 
Fig. 5.—Limits of fatal temperature-time zone. A, pupae and advanced larvae; B, eggs 
Fig. 6. —Fatal temperature-time zones for Bruchus obtectus Say. Active adults; unemerged adults; 
pupae and advanced larvae; eggs 
From these data it is seen that active adults are slightly more 
susceptible to low temperatures. Unemerged adults and the stages 
designated as “ pupae and advanced pupae” have curves practically 
similar. The slight difference is in favor of the latter. The eggs of 
Bruchus obtectus can apparently withstand lower temperatures than 
any other stage. With respect to eggs, however, the criterion used 
