April, '14] HINDS: BLACK WEEVIL CONTROL 207 



doors until corn has passed its "roasting ear stage" and begins to 

 harden up. When this condition of corn occurs, no matter what the 

 date on the calendar, weevils seem to be ready for it and then, for the 

 first time, come to the corn fields in large numbers. In several cases 

 where most carefully studied, the weevils seem to have come most 

 abundantly from the direction of the nearest woods. The earliest 

 maturing corn — regardless of variety — attracts them in greatest 

 numbers and, naturally, the ears that have exposed tips and loose, 

 open husks are then the first and the most heavil}^ attacked. For a 

 brief period most of the weevils may be found upon the earliest matur- 

 ing and most exposed ears on the plants scattered within perhaps 100 

 feet of the outer edge of the field. Gradually they spread farther 

 inward until they are all over the field but naturally the corn from the 

 outer edges of the field and the poorly covered ears throughout the 

 field will always contain more weevils than any other equal number of 

 ears. 



These observations, together with the common experience that 

 early-matured upland corn is nearly always heavily infested, while 

 late matured river bottom corn escapes with practically no injury, 

 point clearly to the feasibility of trap planting to concentrate weevils 

 and of so handling our corn crop upon storage that heavily infested 

 corn may always be kept separate from slightly or uninfested portions 

 of the crop and the former treated for weevil control or fed out first, 

 while the latter may be carried through long storage without necessity 

 of treatment and with little insect injury. 



Futile Remedial Practices 



We have referred to the common practices of allowing corn to stand 

 in the field until after a killing frost, of storing while wet and with the 

 husk on, of sprinkling with salt, etc., to prevent weevil injury. These, 

 and many other popular ideas we have tested carefully both in the 

 laboratory and in large out-of-door storage bins constructed especially 

 for experimental work with the black weevil, and we have found in 

 nearly every case that the}^ have practically no value in weevil control. 

 A few of these ideas deserve specific mention. 



It is commonly supposed that by leaving corn in the field until 

 after a killing frost occurs the weevils on it are killed and that injury 

 during storage is reduced accordingly. On the contrary, ordinary 

 killing frosts such as occur at the beginning of the cold season have no 

 killing efi'ect upon either adults or immature stages. Doubtless the 

 motionless condition of benumbed adults on the cold morning following 

 a frost has misled the casual observer into thinking them dead. 



Storing with the husk on is generally supposed to give more pro- 



