INTRODUCTION 



The impression may be gained that the sugar beet is especially 

 liable to insect injury because of the bringing together of so much on the 

 subject. However, this is not the case. A study of crop insects shows 

 that most crops have an equal number of insect enemies and many have 

 more. It should be emphasized that everything known to good farming 

 practice in beet culture, such as rotation of crops, manuring, clean culture, 

 and timeliness of plowing and irrigating, tends to minimize damage by 

 insects. 



OUTLINE OF THE BULLETIN 



By knowing in advance the structural plan of the Bulletin, reference 

 can more readily be made to any desired part. Hence an outline is 

 given on page 3. Furthermore, the use of this Outline in conjunction 

 with the "Key for Determining Insect Injury to Sugar Beets" (pages 5 

 to 8) may aid in identifying insects. For example, if it is known that 

 damage is being done to the leaves of the beets and that the insects caus- 

 ing it are "Biting" insects, and if it is known that they are not beetles or 

 grasshoppers, then it can, for practical purposes, be concluded that the 

 damage is being caused by either leaf-miners or caterpillars, and by 

 referring to the text cited, a conclusion can in most cases be drawn regard- 

 ing the particular insect causing the damage. If one of the suspected 

 insects has been caught, the Colored Plates (See pages 11 to 27) 

 will greatly facilitate its identification. 



KEY FOR DETERMINING INSECT INJURY TO SUGAR BEETS 



In order to facilitate the use of this Bulletin for reference purposes, 

 a short "Key for Determining Insect Injury to Sugar Beets" has been 

 constructed. (See pages 5 to 8.) If the nature of the insect damage is 

 known, reference to this "Key" should enable one to determine the gen- 

 eral class of insect doing the damage, if not the particular insect. By 

 looking up the descriptive pages cited in the "Key", and by checking 

 the Colored Plates against the suspected insect, if one has been 

 caught, a reasonably strong case can probably be established. 



COLORED PLATES 



It took the artist three seasons to complete the drawings from which 

 the Colored Plates were made. Every insect was drawn directly from 

 a live specimen, and the form and colors are true to life. 



Some of these colored pictures were enlarged. In nearly all such 

 cases a small black and white outline at the left or right of the colored 

 picture shows the natural size of the specimen. The exceptions are 

 clearly noted on the title pages. 



Pictures as well prepared as these carry descriptions much more 

 quickly and accurately than words, especially to persons not trained to 

 think in entomological terms. 



I 



