98 U.S. NATIONAL MUSEUM BXTLLETIN 256 



examples. It occurs in southern Texas and northern Mexico. In Texas 

 its range follows the course of the Rio Grande from near Brownsville 

 as far west as Marfa and Toyahvale in the Davis Mountain country. 

 The northern boundary of its distribution appears to be approximately 

 100 miles from the Rio Grande from Beeville, through Pearsall, the 

 foothills north of Uvalde, westward to Fort Stockton and Toyahvale. 

 it is found very freely in the fields of prickly pear along the river fiom 

 Del Rio to Laredo. Around Uvalde it does not seem to be established 

 in the open country 20 to 30 miles to the south, although it is prev- 

 alent in the foothills 20 miles to the north. In Mexico, M. armata occurs 

 throughout the State of Chihuahua, in Goahuila as far south as Mon- 

 clova, in Nuevo Leon as far south as Monterrey, and in the northern 

 part of Tamaulipas adjacent to the Rio Grande. 



The host plants in Texas are the dominant shrub pear 0, lind- 

 heimeri and its ally 0. cacanapa. In the Fort Stockton and Davis Moun- 

 tain areas it attacks prickly pears of the 0. phaeacantha and 0. engel- 

 mannii types, and it has been recorded on 0. aciculata and the Cylin- 

 dropuntla, 0. kleiniae. In Chihuahua prickly pears and Cylindropun- 

 tias, mainly 0. imbricata were infested generally. 



Adults have been observed in the field in numbers in every month 

 from March to October and less freely in November. The main emer- 

 gence periods are March-May and September-October. There 

 appear to be one complete and a partial generation each year. The 

 beetles live for several months; thus 90 percent of adults collected 

 in July were alive in October and were then ovipositing freely. Again, 

 among beetles captured in October a few still survived in February. 



Eggs have been recorded in April, May, July, August, and October. 

 They may be found on the aerial portions of the plant, placed in scars 

 and wounds or among the spine hairs of areoles near the margins 

 of the segments, and covered with a viscous secretion which hardens 

 rapidly. Many eggs are deposited in small earth cells against the 

 base of the plants just beneath the soil surface. Larvae occur in the 

 butts or in segments well above the ground. The adults are active at 

 night and seek shelter during the day; however, in cloudy weather 

 they have been collected on the plants quite freely until 10 a.m. 

 They travel across the ground from one plant to another; in the early 

 daylight hours they are frequently seen wandering about in the open, 

 apparently in search of prickly pear. 



Moneilema laevigata Blaad 



This species appears to be a northern offshoot from M. armata^ but is 

 more shiny and has less punctures on the elytra than the latter. 



