Sugar Beet Webworm 



Careful watch should be kept of the beets during the last half 

 of June and the latter part of July and early August. Examine 

 the under side of the beet leaves every day or so. 



If young worms are present small pits will be eaten into the lower 

 surface of the leaves. In case such pits occur the little whitish-yellow 

 worms should be found not far away. If the worms are several days old 

 they will be greenish in color, appearing more like the full grown worm 

 (Fig. 6, Plate V, Page 19). At this age they will be found on both sides 

 of the leaves. The edges of the leaves will be eaten away, leaving them 

 ragged, or the entire leaf will be eaten with the exception of the heavy 

 veins. The young leaves at the heart of the beet are usually the last 

 eaten. 



Fig. 11. Field of Sugar Beets showing Work of the Sugar Beet Webworm. Bare 

 areas were weedy when eggs were laid. Balance of field was free from weeds. 



Sometimes the worms will be concealed in webs spun over the leaf, 

 usually near its base. In case small, roundish, dark colored pellets 

 are seen on the leaves, a webworm or some other leaf-eating caterpillar 

 is present. The culprit should be located and his identity established. 



METHODS OF CONTROL 

 Destruction of Weeds 



The sugar beet webworm moth shows a particular liking for lamb's- 

 quarters and Russian thistle as plants on which to deposit its eggs. For 

 this reason if these weeds are abundant in a field of beets the crop is apt 

 to be damaged by webworms if the moths are at all numerous in the 

 vicinity. Volunteer alfalfa is also a menace to the crop. 



The effect of allowing weeds to grow in a crop of beets is strikingly 

 illustrated by the cut on page 71 (Fig. 11). 



71 



