Sugar Beet Webworm 



Very often a few eggs in one part of a field indicate that in some 

 other portion there are many more. Not infrequently the moths lay eggs 

 by the hundreds and thousands over a very small area. This is quite 

 as apt to be in the center of the field, or at least some distance from the 

 border, as near the edge of the field. All weedy spots should be carefully 

 examined and the weeds removed as soon as possible, as these are often 

 the places where the injury starts and spreads to the entire field. 



It is hard for a person who has not seen a severe outbreak of web- 

 worms to realize that what appears to be but a few small worms is capable 

 of causing the loss of several dollars worth of beets. This fact has been 

 the cause of a great deal of the loss in the past. 



If eggs or young worms are found it is time to get your spray 

 machine out, or your neighbor's if you do not have one of your 

 own, and provide a supply of Paris green ready to apply as soon as 

 the eggs begin to hatch. 



V- 



As the young 

 worms feed entirely 

 on the under side 

 of the leaves for 

 several days after 

 they leave the eggs 

 and do not eat away 

 the upper surface, 

 their presence is not 

 suspected, many 

 times, until they 

 are so far developed 

 that much damage 

 is done before they 

 can be controlled. 



When first 

 hatched the worms 

 are so small that 

 their capacity for 

 doing damage is 

 limited. As they 

 increase insize their 

 appetites become 

 almost insatiable. The rapidity with which they will completely strip a 

 beet field of leaves is almost beyond belief. Each worm will eat several 

 times its own weight of beet leaf every day. So rapid is their work that 

 although there is no apparent injury today, tomorrow or the next day 

 large spots in the field may be completely defoliated. 



These spots very often occur in the center of the field, thus they are 

 overlooked unless it happens that the grower is cultivating or irrigating 

 at the time. 



Fig. 10. Sugar Beets badly damaged by Webworme 



70 



