Alfalfa in Kansas. 



367 



INSECTS INJURIOUS TO ALFALFA. 



By GEO. A. DEAN, Entomologist, Kansas State Agricultural College. 



Like most of the field crops, alfalfa suffers from the attacks of many 

 kinds of insects. No part of the plant escapes attack. The roots, stems, 

 leaves, flowers and seed are eaten by a great variety of them. Even 

 alfalfa hay is the special food of certain caterpillars. A field of alfalfa, 

 especially when in bloom, is alive with insects, some of which are bene- 

 ficial while others are very injurious. Many of those which rely wholly 

 or in part on alfalfa for their food are too scarce to do appreciable 

 damage. However, there are several species which may appear in such 

 large numbers that the crop in large sections is destroyed and great 

 damage is done. It is with these injurious species that this discussion 

 is concerned. It should also be noted that many of the insects that are at- 

 tacking alfalfa are those that are classed as clover insects, and thus are 

 named after the clover plant rather than the alfalfa. 



THE CLOVER-ROOT BORER. 



(Hylastinus obscurus Marsham.) 



The adult, a small, dark-brown, hard-bodied beetle, about one-eighth of an 

 inch long. The larva a dirty-white, footless, maggot-like worm about 

 one-eighth of an inch long, yellow head, brown jaws, and is found 

 within the main root of the plant, eating out the contents. (Fig. 310.) 



FIG. 311. Clover-root 

 borer. Larva or grub ; 

 enlarged. (After Webster, 

 U. S. Dept. Agr.) 



FIG. 310. Clover- root 

 borer (Hylastinus ob- 

 scurus). Adult insect; 

 12 times natural size. 

 (After Webster, U. S. 

 Dept Agr.) 



History and Distribution. 



This insect is a native of Europe, where it has been known for more 

 than a century. In 1878 it became destructive in New York, but prob- 

 ably occurred in the United States long before that date. It is now dis- 

 tributed from the Atlantic to the Mississippi valley states, and since it is 

 working rapidly westward it will probably not be many years before it is 

 as serious a pest in the alfalfa-growing states as it is in the clover- 

 growing states. 



