Sugar Beet Webworm 



At blocking and thinning time this field was quite free of weeds 

 except a strip running entirely across the picture from right to left 

 and indicated by the bare spots at either side. The hand labor began 

 thinning before the webworms appeared, cleaning out the rows, including 

 the center portion of the weedy strip, but leaving the weeds in the sec- 

 tions at each end represented by the bare spots. They then moved to 

 another part of the field. In the meantime the webworm moths deposited 

 thousands of eggs on the weeds left. 



When the labor returned to this part of the field both the weeds and 

 the beets among them were stripped of their leaves. The beets on that 

 part of the weedy strip that had been cleaned out earlier were not dam- 

 aged. The worms were just moving to the beets surrounding the weedy 

 patches, but a thorough application of Paris green applied according to 

 the instructions given later killed them and no further damage was done. 



Furrow Trap 



Weedy ground bordering a beet field is very often as bad as weeds in 

 the field. As soon as the worms have destroyed the weeds on which they 

 hatch, hunger compels them to search for food. At such times they 

 travel in armies, devouring whatever green thing comes in their way. 

 A furrow plowed about the field and a small stream of water kept running 

 in it will prevent the advancing worms from entering it. Newly cut 

 alfalfa thoroughly sprayed with Paris green placed in the path of the 

 oncoming army will destroy the worms by thousands. 



Irrigation 



In case both the moths and worms escape your observation and 

 you are not aware that your crop is being damaged until a large por- 

 tion of the leaves are eaten, the damage can sometimes be lessened by 

 applying water to the crop, thus stimulating the growth of beets. This 

 is especially true if the season is dry. 



Poison 



After the webworms have appeared in a field the only way to prevent 

 loss is to kill them by spraying with some poison. Paris green seems 

 best for this purpose. Being prepared for quick action as soon as 

 the proper time comes to begin the fight is extremely important. 

 Have all your forces mustered, all equipment in working order 

 and a good supply of Paris green on hand. When the time 

 comes strike and strike hard, working as rapidly as possible. 



The most vulnerable period of the webworm's life is during the first 

 few days after it leaves the egg. There are two reasons why this is the 

 best time to fight this enemy of the beet crop : 



(1) If killed when young the worms will not have time to do much 

 damage, which means that they will not eat as much leaf before 

 dying as they would if they were older. 



(2) It requires less poison to kill the young worms. 



However, do not think that because less poison is needed to 

 kill the young worms that less should be used, for this is not the 

 case. Too diluted a poison will mean an unnecessary consumption of 

 leaves to bring about the death of the worms. 



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