4 BULLETIN 443, U. S. DEPAETMENT OF AGRICULTURE. 



to the square rod over all of the infested section. It is plainly evi- 

 dent that the tremendous abundance of the pest constitutes a grave 

 menace to any crops attacked. 



CROPS AND GRASSES ATTACKED. 



The range caterpillar devours the range grasses down to, but not 

 including, their roots. It feeds upon all the grama grasses, bunch 

 grass, foxtail, side oats, wild rye, blue-joint, mesquite grass, buffalo 

 grass, and even bluegrass on lawns. About 40 different kinds of 

 grasses are included in the determined list of food plants of this 

 insect. 



One of the most important developments noted during the past 

 two years is that of the apparent change of the food habits of the 

 range caterpillar. In many instances, in addition to its damage to 

 the range grasses, it has seriously injured cultivated grains and 

 forage crops, incluchng millet of various kinds, wheat, oats, barley, 

 milo maize, Sudan grass, and, to a slight extent, corn and alfalfa. 

 Of the cultivated crops, millet has appeared to suffer the most from 

 attacks of this caterpillar. The damage to such crops has usually 

 occurred where isolated farms were surrounded by infested range 

 pastures. As the range country of New Mexico is rapidly becoming a 

 dry-f arming and irrigated agricultural district, it is evident that the 

 range caterpillar, unless checked, is likely to become a serious pest 

 to cultivated crops, and therefore of as much importance to farmers 

 as to stockmen. However, it is at present primarily destructive to 

 the range pastures. 



CHARACTER OF THE INJURY. 



The range caterpillar injures the crops in two ways: First, by eat- 

 ing the range plants down to the roots, over large areas, and in the 

 case of cultivated crops by devouring the leaves ; second, by poison- 

 ing the uneaten plants with the caterpillar spines, which it sheds 

 in crawling from place to place or during the process of molting. 



INJURY CAUSED BY PLANT FEEDING. 



The injury caused by the range caterpillar in feeding upon various 

 plants is the more important of the two. as it deprives the grazing 

 stock of food and renders such cultivated crops as millet and Sudan 

 grass unfit for forage. The greatest amount of damage is done during 

 July and August, although some destructive feeding takes place 

 during late June and early September. When the caterpillars are 

 very numerous the range pastures for many miles will have the 

 appearance of having been clipped by a lawn mower. Under these 

 conditions many of the caterpillars die through lack of sufficient food 

 to enable them to complete their growth. 



