February, '16] ENTOMOLOGISTS' DISCUSSIONS 129 



Mr. William Hayes: I have had no experience in that hne but I 

 thought it was mice that carried off the missing bugs. I have always 

 kept them in open cages. I do recall one instance sometime in the fall 

 that I wondered at the disappearance of several bugs out of a certain 

 cage. It is possible they might have flown away. 



Mr. Z. p. Metcalf: I do not attribute the sudden disappearance 

 of the Southern corn bill bug from our open cages to the work of 

 mice for I actually saw them fly away. 



Mr. F. M. Webster: I would like to ask if anybody has any proof of 

 their leaving the field at all. Where corn follows corn, if you alternate 

 by a crop of cotton, no difficulty results with the next crop. One of these 

 species was worked over and published by the Bureau of Entomology. I 

 believe where corn has followed corn for two or three years, a rotation 

 of crops, except of kafir or something of that sort, is necessary. 



Mr. Z. p. Metcalf: In our experience in North Carolina we have 

 not been able to find any constant differences where corn follows corn 

 or where corn follows cotton. As a general principle the corn bill bug 

 is worse where corn follows corn but this is not always the case. And 

 from our experience it is not safe to recommend crop rotation as the 

 only remedy necessary for the control of the Southern corn bill bug. 

 I have in mind now a field of considerable elevation where the corn 

 bill bug was worse, although the field was in cotton the year previous, 

 than it was in an adjoining field of lower elevation and hence more 

 hkely to be attacked by bill bugs that had been in corn the year pre- 

 vious. This same condition has been noted in various localities and I 

 would like to ask Professor Webster, therefore, if there was not some 

 other factor of more importance than crop rotation involved in the 

 field of corn on the "Shannon house place" which is illustrated in his 

 bulletin on the "Curlew bug." A heavy application of fertilizer will 

 make corn grow very rapidly and escape the attack of the corn bill 

 bug. And in the past cotton farmers have been in the habit in North 

 Carolina, at least, of making heavy applications of fertilizer to cotton 

 and none or only a very light application to corn. A great deal of 

 this fertilizer might be held over in the soil until the following year 

 when it would make its presence felt on the corn crop. Time of plant- 

 ing is also a very important factor in the control of the corn bill bug. 

 Either one of these factors might account for the fact that one could 

 tell to the very row which part of the field had been in cotton the 

 year previous and which part had been in corn but from a pretty 

 extended study of this insect in the field, it is hard for me to believe 

 that there would be anything in the mere fact that the field had been 

 in cotton the year previous to prevent the corn bill bug from attacking 

 the corn. 



