SHUCK PROTECTION FOR EAR CORN, 3 



Ears were classified as having good shucks if the shucks extended 

 beyond the tip of the ear and closed more or less tightly about the 

 silks. Most of the so-called good shucks were not ideal or such 

 as would be the breeder's aim, but were only better than those 

 classed as poor shucks. 



If a hole or holes had been cut through a good shuck by a 

 worm, the ear was put in the class of good shucks with worm- 

 holes; if no such openings had been made, the ear was classified 

 as good shucks without wormholes. Only such wormholes as 

 were cut through the shucks were considered. It was found, after 

 removing the shucks, that some of the ears in the class good shucks 

 without wormholes had been attacked by worms, too. They had 

 entered tlirough the silk channel and had either left through the 

 same channel or died. 



While the shucks were being removed an examination was made 

 for the work of the earworm and for insect infestation, mold, and 

 discoloration. The number of ears infested with insects or damaged 

 by molds and discoloration was thus determined for each class of 

 shuck covering. 



At the time the notes were taken the earworms (Heliothis obsoleta 

 Fab.) had completed their work. The black weevils (fig. 1) and a 

 group composed of two or more species of small reddish brown beetles 

 (fig. 2) were practically all the insects which infested the ears at that 

 time. In this bulletin the black weevils are therefore termed 

 "weevils" and the small reddish brown beetles are termed "beetles." 



In making counts an ear was considered infested when only a 

 single insect was found inside the shuck covering. 



Practically without exception ears infested with weevils were also 

 infested with beetles. For this reason the number of ears infested 

 with beetles is the same as the total number of ears infested with 

 insects. 



The results of the investigations of the relation of the shuck cover- 

 ing to insect infestation are summarized in Table I. 



Table I. — Relation of the shuck covering of corn to insect infestation in the field. 





Percentage of ears— 



Kind ol shuck covering. 



In each 

 class of 

 shucks. 



Infested with — 





Weevils. 



Beetles. 



Poor 



48 

 28 

 25 



62 

 38 

 9 



96 



Onodj wit.h wormholpfs 



93 



fi-onrl.j withoiit wormhnlfts . , 



56 







Total 





38 



85 









