Introduction 



KEY FOR DETERMINING INSECT INJURY TO SUGAR BEETS 



A. Leaves of plant wilted while those of surrounding plants re- 

 main normal. 



1 Plants cut off above the surface of the ground, at varying depths 

 below, or with portions of the root surface eaten away, leaving 

 shallow depressions or deep pits with darkened walls, 

 a. Plants small. Damage occurring before or shortly after 

 blocking and thinning. 



* Plants cut off at or just below the surface of the ground. 

 Damage most apt to occur where beets follow alfalfa 

 or grain, timothy or abandoned crops, and on fields ad- 

 jacent to alfalfa. 



Look for Cutworms (pages 38-48). 



** Plants cut off an inch or so below the surface of the 

 ground. Tip of root as pulled from the ground dark, 

 almost black. Damage most apt to occur where beets 

 ■ follow alfalfa, sod, pasture or meadow. 



Look for : White Grubs (pages 48-52) ; 

 Wireworms (pages 52-54). 



b. Beets larger. Damage occurring from time roots attain the 

 size of one's finger until harvest. 



* Plants always cut off above surface of ground or with 

 deep cavities pecked into the crowns. Damage most 

 apt to occur near standing alfalfa or waste land over- 

 grown with weeds or other tall growth. 



Damage caused by Pheasants. 

 ** Plants never cut off above the surface of the ground. 



° Portions of root surface eaten away, leaving shallow 

 depressions with rough darkened surface. Root 

 often entirely eaten off several inches below the 

 surface of the ground. Damage usually occurring 

 where beets follow sod, pasture or meadow, or on 

 river bottom land. 



Look for White Grubs (pages 48-52). 



oo Portions of root surface eaten away, leaving small, 



deep, dark-walled pits. Roots of large beets never 



entirelv eaten off. Damage most apt to occur 



where beets follow alfalfa, sod, pasture or meadow. 



Look for Wireworms (pages 52-54). 



2 Plants not cut off. Portions of root surface not eaten away. 

 Leaves often dull, dark green, as though plants were suffering 

 from lack of moisture; or leaves yellowish green. 



