February, '10] HIXDS AND TURNER: CARBON DI-SULFID 49 



quently sufficient to destroy a large percentage of the feeding value of 

 the corn before the middle of the winter. In some localities, partic- 

 ularly where the land is overflowed during the winter, it appears that 

 the corn is but little affected, while upon uplands especially, ears some- 

 times contain a hundred or more adult weevils before the first of 

 November. Badly infested corn is almost worthless, since it is not 

 attractive even to hogs. Horses and mules frequently refuse it 

 entirely. 



Besides their effect upon the feeding value, the weevils injure very 

 materially the value of the seed for planting. Kernels from which 

 weevils have emerged will rarely germinate at all, and if they start 

 to grow the plant is weak and backward. In the experiments to test 

 this effect, sound kernels were placed in germination boxes in compar- 

 ison with an equal number which showed but slight traces of weevil 

 injury and also with another lot of kernels from which weevils had 

 emerged. The germination from sound seed was perfect and the 

 growth of the plants vigorous. The slightly injured lot gave 20 per 

 cent germination, but only 10 per cent yielded plants of normal 

 strength. The badly infested lot did not sprout (PI. 4, fig. 1). 



In another series of tests, corn was selected which showed an amount 

 of weevil injury which was considered as a fair average for the condi- 

 tion of corn used for planting at planting time. One hundred kernels 

 taken as the average ran on one side of the middle of an ear, gave 80 

 per cent germination with about 65 per cent of normal growth. One 

 hundred sound kernels selected from the opposite side of the same 

 ear gave 100 per cent of germination with normal growth (PI. 4, fig. 2) . 



The results of these and numerous other germination tests show that 

 weevil injury is in all probability responsible to a considerable extent 

 for irregular stand and lack of uniformly normal growth in the corn 

 fields of the badly infested area. Evidently this is quite an important 

 factor in keeping down the average production of corn to the low 

 yield of about 13 bushels per acre which has hitherto been obtained. 



Among the species of insects which injure corn, the boU worm or 

 corn ear worm (Heliothis ohsoleta Fab.) is the first of importance in 

 the time of its attack. Besides the injury which these worms do di- 

 rectly, it is evident that they prepare the way for increased injury by 

 other species, which later attack the grain. A considerable degree of 

 injury is inflicted by some of the grain moths, both before and after 

 the corn is harvested, but the principal injury after harvesting is 

 attributable to various species of Coleoptera, among which we have 

 found the following particularly abundant : Calandra oryza, Cathartus 

 gemellatus, Cathartus advena, Silvanus surinamensis, Tribolium fer- 

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