22 



plantiDgs of sweet corn for garden use, so that the loss from injury to 

 plantings of this character can only be surmised, as must also be the 

 theoretical value of the culture of this crop to the South, where its 

 cultivation is now largely prohibited, as previously stated. Giving 

 due consideration to all of these points, it is believed that an estimate 

 of an average annual injury of 25 per cent would be within the limits 

 of reason. 



The sweet corn pack of 1900, as given by the Twelfth Census, was 

 6,185,624: cases of 24 cans each, with a value, based on the minimum 

 price of 60 cents per 12 cans, of $7,422,748.80. On the supposition 

 that boll worm injury to sweet corn throughout the country was equal 

 to 25 per cent of the reported pack, the loss is found to amount to 

 $1,855,687.20. 



Bollworm ravages to field corn are most severe in the Southern 

 States, where the percentage of infested ears one year with another 

 will probably not fall below 75, and will often, as during the past two 

 years at least, reach higher. No accurate data are at hand to indicate 

 the average annual percentage of infestation of corn throughout the 

 great corn-growing regions of the Central, Eastern, and Western 

 States, but it will probably average at least as much as 50 per cent, 

 and often much more. Injury to varieties of field corn is not so 

 extensive as in the case of sweet .corn. Usually only a certain small 

 percentage of the kernels are eaten from the tip end of the cob, 

 and the large cavities and extended longitudinal channels eaten out 

 b}^ the larvae in sweet corn are in field corn only occasionally to 

 be found. The destruction of the silk and the exit holes of the 

 caterpillars, however, afford an entrance to rain, especially before the 

 ears have lost their more upright position, which, in connection with 

 molds and ferments, may work more serious injury than the larvae 

 themselves. However, the actual destruction of kernels used by the 

 larvae as food amounts, in the aggregate, to a very important loss. 

 The average of seven individual boUworms, fed on soft corn kernels 

 in the laboratory, was 40 kernels each, during the period of their 

 growth. Allowing 900 grains to the average ear, this would mean a 

 possible loss of about 4.5 per cent of the grains of infested ears. 



By actual count of the kernels of a series of infested ears of field 

 corn, as grown at Paris, Tex., it was found that the percentage 

 destroyed was 15, representing, often, the work of from one to three 

 larvae. It is to be noted, however, that the kernels of the tip end of 

 the ear, the portion usually infested by the bollworm, are smaller 

 than those farther back on the cob, and would probably average not 

 more than one-half the weight of full-sized grains. The percentage 

 of injury as determined by weight would, therefore, be not more 

 than 7i. In view of these figures it is believed that the bollworm 

 may reasonably be charged with an annual destruction of at least 2 



