34 U-S. NATIONAL MUSEUM BULLETIN 256 



of western Texas to southern Arizona. The eastern limits of its range 

 appear to extend from Henrietta, on the Oklahoma boundary, due 

 south to Austin, thence in a westerly direction along the edge of the 

 plateau to Rocksprings, and south to the Rio Grande in the foothills 

 country west of Del Rio. It occurs right across western Texas from the 

 Panhandle in the north to El Paso, through the greater part of New 

 Mexico except the northern portion, and in southern Arizona. In 

 southern Arizona, the western limit would seem to be the Quijotoa 

 Mountains between Tucson and Ajo; from New Mexico the insect 

 extends southward through the Mexican State of Chihuahua to its 

 southern boundary. 



The food plants comprise the bushy prickly pears Opuntia engelmannii, 

 0. phaeacantha, and various other related species, and low-growing 

 plants of the 0. tortispina group. The species is prevalent in various 

 parts of its extensive distribution. In west-central Texas it is often 

 abundant on the Edwards Plateau especially around Marble Falls 

 and in the Albany-Sweetwater region. Fartlier west. Fort Stockton 

 is a favored area. In New Mexico, it is not uncommon at Mesilla 

 Park and Silver City, while at Douglas, in the southeastern corner 

 of Arizona, colonies of larvae were numerous in an extensive area of 

 approximately 60 square miles of a low-growing Opuntia of the tor- 

 tispina type. In the Tucson sector of southern Arizona, the species is 

 rarely found in prickly pears growing in the open mesa country, 

 but occurs rather freely in many places in the foothills and lower 

 valleys of the various mountain ranges. 



The larvae cause considerable injury. As they frequently tunnel 

 downward into the basal segments, well-grown bushy plants are often 

 killed completely. In west-central Texas this insect appears to exercise 

 an important controlling effect on Platyopuntias. 



There is one generation annually. Pupation takes place in August 

 and September, and moth emergence from late August to the end of 

 October. The females usually deposit in excess of 100 eggs. In 1928 

 material from various localities yielded an average of from 116 to 128 

 eggs per female. Other records of averages are: 



Number of Average number of 



females eggs deposited by each 



132 110 



40 129 



261 64 



10 137 



The last record was obtained from moths that emerged at Uvalde, 

 Texas, from pupae collected in Chihuahua, Mexico. Eggsticks deposited 

 under cage conditions gave an average of 45 eggs per stick; the largest 

 contained 96 eggs. 



