30 U.S. NATIONAL MUSEUM BULLETIN 256 



The larvae are either solitary or gregarious in habit. Among the 

 gregarious forms the most interesting are the species of Melitara and 

 Cactoblastts, since the females deposit the eggs in the form of chains, 

 or sticks, to which the term "eggstick" is generally applied; the egg- 

 sticks may contain as many as 150 eggs, although the usual number is 

 from 35 to 80. The species of Melitara occur throughout the United 

 States prickly pear region, except in California; thus distribution 

 extends into northern Mexico but apparently does not reach the 

 great cactus region of the Central Plateau nor the eastern and western 

 coastal strips; the larvae are blue, blue-grey, or blackish-blue in color. 

 The genus Cactoblastis, with almost identical larval, pupal, and egg- 

 laying habits, is found in southern Peru, southern Brazil, Paraguay, 

 Uruguay, and Argentina; the larvae are bright orange or orange-red 

 with transverse rows of black spots. In the great intervening region 

 between northern Mexico, southern Peru, and southern Brazil, no 

 gregarious phycitid of the Melitara-Cactoblastis egg-laying habit is 

 known. The species of Olycella, inhabiting the United States and the 

 greater part of Mexico, deposit eggsticks, but these are shorter and 

 contain many fewer eggs, usually 8 to 12, very rarely up to 30; the 

 larvae are gregarious in their young stages, but soon become solitary. 

 Insofar as is known all other cactus phycitids deposit their eggs singly 

 or two or three together. 



LAETILIA Ragonot 



LaetlUa coccidivora (Comstock) 



This insect is a well-known enemy of various Coccidae in the United 

 States and is a common predator of Dactylopius species. Apparently, 

 however, the larvae occasionally vary their diet, since adults have 

 been reared from larvae feeding in Opuntia flowers at Uvalde, Texas. 



MELITARA Walker 



This genus appears to be restricted to the United States and northern 

 Mexico. The larvae arc gregarious tunnellers in various Platyopuntias. 

 In color they vary from light grey-blue to black-blue, assuming a 

 shade of intense translucent blue immediately prior to pupation; 

 larvae of M. prodenialis are usually darker than those of the other forms. 

 The cocoons are of the typical Cactoblastis type, to be described on 

 page 49; those of M. prodenialis tend to be less stoutly constructed than 

 are those of the other species. They are found among debris at the 

 base of or near the attacked plants, in dried-out prickly pear segments, 

 or, in one form, within the feeding cavities made by the larvae. The 

 adults have a wing expanse of 30 to 50 mm. As with Cactoblastis^ the 



