. 394 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



the cowpeas could have an opportunity to dry and retard the develop- 

 ment of the mold. On November 7th, adult weevils began to emerge. 

 The vials were examined daily and all emerged adults were removed. 

 On December 9th, after 101 adults had emerged, it was found that the 

 vials were becoming infested with mites, Pediculoides ventricosus, 

 which made it necessary to kill all within the vials. The cowpeas 

 were then dissected and the contents tabulated. 



Within the "mercury vial" there seemed to be no activity. No 

 borings or frass exuded from the cowpeas ; no larvae bored openings in 

 the seed coats, and there was no evidence of the lack of proper ventila- 

 tion. On October 6th, when it was thought that all the weevils were 

 dead, seven cowpeas were dissected. The last one contained two 

 half-grown larvae which were alive but were very inactive. The re- 

 maining 93 cowpeas were set aside for further observation. On De- 

 cember 9th a very small amount of m_old appeared in the vial. By 

 January 11th the mold had not increased to any appreciable extent, 

 and no weevils had emerged; so the cowpeas were dissected and the 

 contents tabulated. At this time all the weevils were dead. 



Adult': Larvae 



OQ o 6-0 S^ ^^ ^ -^ -^t '*'> c% 



do d^'S'^6dc^S3°"°°°S°!SP 



;z;0 Treatment 2; K w ;?; g ^fc 2 12; m ^ ai ^5 m 



100 Mercury 800 643 20 80 244 299 



100 Check 920 814 101 79 61 29 82 154 307 



The above table shows that in the mercury vial only 20 larvae be- 

 came full-grown and only SO more became half-grown, while in the 

 check vial 101 adults emerged, 79 were ready to emerge, 61 had be- 

 come pupae. While all weevils in the mercury vial died, and while 

 only 101 emerged from the other vial, there is no doubt that most of 

 the unemerged adults and pupae, and many of the larvae from the 

 check vial would have emerged if the mites had not made it necessary 

 to kill them. 



In the foregoing experiments the presence of the mercury was the 

 only thing that could possibly have caused the eggs and larvae to fail 

 to develop. Only in one case was the mercury in contact with cowpeas, 

 and then it was not in contact with the eggs. The mercurv did not 

 seem to diminish in amount, and as Dr. K?nnan said, "It could be 

 used over and over again with no apparent loss." 



While the foregoing m-ay not be of practical use in warehouses be- 

 cause of the initial cost of the mercury, it is of scientific interest and 



