FIFTH ANNUAL REPORT STATE ENTOMOLOGIST 143 



tlie insects were feedinj^ in the fall is removed and the field is set with 

 plants. The hunj^ry caterpillars searching about for food, make 

 short work of such crops as cabbages, beans, sugar beets, etc. In 

 2 few instances we have known a sugar beet field completely eaten 

 ofif by this species so that it was necessary to plant the ground to 

 another crop that could be matured before the end of the season. At 

 Miles City our attention was called to a small field planted with 

 onion sets. The onions had made a good start when the cutworm 

 attacked them and completely ate off the tops and followed them 

 down inside and ate out the entire bulbs, except the dry outer walls. 

 Scarcely an onion was left. 



The cutworms molt from time to time but their appearance 

 does not change materially as they grow larger, though the prevail- 

 ing color-cast is much lighter in the older stages. The individual 

 caterpillars vary considerably in depth of color. 



RANGE OF FOOD. 



The caterpillars eat a very wide range of plants and have not 

 refused to eat any kind of food placed in their cages. In grain 

 fields they show a distinct preference for the grain, paying little 

 attention to the various weeds to be found there in abundance. The 

 succulent tops of beets they eat readily. A bulletin of the Colorado 

 Experiment Station, by Mr. S. Arthur Johnson (Bull. 98, p. 17) re- 

 cords that in 1903, near Denver, they ate an entire field of alfalfa. 

 Ordinary lawn grass (blue grass) is eaten readily and we brought 

 to full size a large number of the caterpillars in our greenhouse in 

 the winter of 1906-7 by placing in their cages pieces of green lawn 

 sod from over steam pipes passing from one building to another. 

 They are a general garden pest and we do not consider that any 

 crops, with a possible few exceptions, are exempt from them. Pro- 

 fcsor E. V. Wilcox recorded the following plants as being eaten by 

 Chon'aa gratis auxiliaris : "Clover, lupine, alfalfa, sanfoin, cabbage, 

 horse radish, radish, mustard, turnips, shepherd's purse, timothy, 

 bluejoint, red-top, wheat, oats, rye, barley, thistle, Balsaiiurr}ii::a, 

 cactus, beets, strawberry, cherry, apple, peach, apricot, prune, plum, 

 raspberry, currant, gooseberry, blackberry corn, peas, celery; to- 

 mato", onion, avens, larkspur, rhubarb, dandelion, and num.croas 

 other native grasses." 



