NEW MEXICO EANGE CATERPILLAR AND ITS CONTROL. 3 



covered with clusters of sharp, poisonous spines. They remain in this 

 stage about four weeks, and, owing to their large size, greediness, and 

 great numbers, do their greatest damage at this time by devouring, 

 or rendermg unfit for grazing, most of the range grasses, and certain 

 cultivated crops to a more limited degree, over large areas. 



WHERE THE RANGE CATERPILLAR OCCURS. 



At the present time the range caterpillar is known to occur in the 

 northeastern and south-central portions of New Mexico, with a 

 scattering infestation along the adjoining '' Pan- 

 handle'' of Texas. During the season of 1915 

 small colonies were found at Duran and Corona, 

 in southern New Mexico. The parent moths have 

 been found outside the hmits mentioned, but in 

 these locahties no caterpillars have ever been dis- 

 covered, although the surrounding country has 

 been searched each year for evidence of their 

 presence. It seems possible that this pest may 

 eventually be found far to the southward of its 

 present kno^^ai hmits, but the msect is now of 

 great economic importance only in the north- 

 eastern corner of New Mexico, in the counties of 

 San ^Miguel, Taos, Mora, CoKax, and Union. 



ITS ECONOMIC IMPORTANCE AND GREAT ABUN- 

 DANCE. 



In many parts of the section just mentioned 

 these range caterpillars, or "grass-worms," as 

 they are popularly known, constitute a great fig. 3.— The New Mexico 

 menace to successful stock raising and farmmg. 3uS'on wcTd 

 When the present investigations began, many stem, to avoid the 

 stockmen and farmers were of the opinion that on ^^^^^^ ""(cTAiLH] 

 account of the ravages of this insect it would be 

 necessary to abandon stock raising in that part of New Mexico, 

 which, as ha.s been stated, includes an area of approximately 30,000 

 s([uarc miles, or about the area of Maine. 



Owing to the constantly decreasing area devoted to stock raising, 

 tlie economic; importance of this caterpillar can not bo overestimated. 



The gi-eat abundance of thc;se caterpillars should be taken into 

 consideration in estimating the damage caused by the insect. In 

 lOl.'i a total of oOO full-gr'own cntc^rpiUars were counted f(ieding upon 

 an averages s((uare rod of pastiijc, 6 miles northeast of Las Vegas. 

 This is at the ratc^ of .'iO, 720, 000 of these large caterpillars per square 

 niil(\ Many squan; miles in this section were similarly infested. 

 The caterpillar is commonly found in niinibcns of from 100 to 200 



