54 The Bulletin. 



if left indefinitely; fumigation is more effective during warm weather; 

 never attempt it when temperature is below 60 degrees. A second treat- 

 ment (stronger) should be given after a week or two if it appears that 

 the first was not effective." 



Prof. E. I. Smith, after Avorking in J^orth Carolina, became con- 

 vinced "that carbon bisulphide, at any reasonable strength, cannot be 

 successfully used in ordinary corn cribs, grain boxes, or storerooms. 

 Small quantities can be fumigated in absolutely tight boxes or barrels by 

 using about one ounce to three bushels; the top must be air-tight, not 

 simply covered with blankets or canvas. Fumigation should continue 

 for about 24 hours." He found that some stages of the insects would 

 survive treatment; especially eggs and pupse. 



Which leads the present writer to insist that one may expect imperfect 

 results, but still this fumigation method is the best known when once 

 the corn is infested. Have the corn free to begin with, if possible, by 

 cleaning the bins, and perhaps even throwing out ears already visibly 

 infested ; have the bins tight, so that they can be fumigated if necessary ; 

 use enough of the bisulphide to make allowance for leakage through such 

 cracks as there may be ; and finally, if the treatment seems not to have 

 killed all, give a second treatment a week or two later to kill larvae and 

 adults which may have developed from eggs or pupse which survived the 

 first treatment. 



Caution. — Carbon bisulphide is like benzine in its nature, both the 

 liquid and its fumes being very inflammable, and no light or fire of any 

 description can be brought near while the fumigation is going on, not 

 even a lamp, cigar, or pipe. After the fumigation is over, open the bin 

 (box, or room) and air out. If these cautions are heeded the material 

 is safe to use. 



Heat. — It has long been known that insects are killed by high temper- 

 atures, and this fact has been made use of recently in some striking tests 

 by Mr. George A. Dean of the Kansas Experiment Station in ridding 

 flour-mills of insects by the heat method.' In summarizing his work, he 

 says: 



"A temperature of from 118 to 125 degrees is sufficient for any part 

 of the mill. (This temperature should be held several hours to allow the 

 heat to penetrate all the infested parts (of the mill)." But he also says : 

 "I would not recommend heat for killing insects in stored seeds and 

 grain. In case they are stored in small quantities, the heat method would 

 be entirely satisfactory; but if in large quantities it would require too 

 much heat to penetrate to center of bins." 



LESSER CORN INSECTS. 



We have devoted the greater part of this Bulletin to those insects 

 which are regular serious pests of corn in this State. It now remains to 

 make brief mention of a few which are of minor importance or which 



iJour. Ec. Ent., Vol. 6, p. 40, Feb., 1913. 



