75 



Such is apparently not the case, however, as two experiments made 

 on corn plants show. Two average youno- plants of field corn grow- 

 ing in the laboratoiy garden were chosen and watched until maturit3% 

 with the result shown below: 



Table XXVII. — Effect of bollworm i7ijury to young corn. 



Experiment 1. 



Experiment 2. 



Date. 



Observation. 



Date. 



Observation. 



May 14 

 May 15 



May 19 

 May 20 



June 2 



June 11 



June 21 



Placed a one-fourth grown larva in bud 

 of corn plant 2i feet high. 



Larva has eaten from one of the partially 

 uncurled leaves in the bud; damage 

 slight. 



Bud is now badly damaged. 



Damage is greater, but growth is not im- 

 paired. 



Plant now 7^ feet high; shows serious 

 damage, but is still healthy. 



Now in tassel and silk; is one of the 

 healthiest plants in the garden. 



Is bearing two fine ears. 



May 17 



May 18 



May 19 

 I*Iay 20 



June 11 

 June 21 



Placed three larvae (one-fourth, one- 

 fourth, and one-half grown) on corn 

 plant. 



Some damage down in bud is notice- 

 able 



Much injury is now noticeable. 



Damage increased; one larva visible 

 in the bud. 



In tassel and silk; quite healthy. 



Is bearing a large, healthy ear. 



In these two cases, at least, the plants, although much disfigured 

 when 3^oung, were fully up to the average in productivity^ later in 

 the ..sjeason. 



At times the feeding of the larv« in corn buds produces a def ormit}^ 

 resulting in the failure of the developing leaves to unroll normally, 

 but such instances are too rare to have any bearing on the question of 

 bollworm injury by this brood. 



The injury to tassels (PL VII, fig. 2), which occurs later in the sea- 

 son, is of small economic importance also, since the few which may 

 be partial^ destroyed must have but small effect on the pollen produc- 

 tion of the field. 



DAMAGE TO EARS OF CORN. 



It is in the ears that the real damage and loss occurs, but this injury 

 is frequentW overestimated. In ears of early swxet corn it is not 

 exceptional for the larva to bore directl}^ down the ear, as shown in 

 Plate VIII, figure 2. In this case the actual number of grains destroyed 

 may be considerable, and the filthy excrement distributed over so large 

 a space favors decay and subsequent molding of the ears, thus mak- 

 ing the corn unfit for the market or table use. Feeding normally 

 about the apical portion of the ear, the part affected scarcely ever 

 amounts to more than one-fourth or one-fifth of the ear. But the 

 extent to which sweet corn is infested, as compared with field corn, 

 makes the loss to this crop proportionalh^ heavy. 



In feeding on the larger and more rapidly hardening ears of field 

 corn, injury is usually confined to the silk and apical portion, as shown 

 on Plate VIII, figure 1. The exact quantit}^ consumed by each larva 

 is not readily determined, since it is quite variable. After the eggs have 

 hatched the silks may furnish the food until the larva is from one- 



