CACTUS-FEEDING INSECTS AND MITES 37 



ments, except during the winter months. This southern Texas Melitara 

 does not appear to be as destructive to prickly pears as M. doddalis 

 and M. prodenialis. 



Parasites. — Natural enemies reared from the pupae are the tachinid 

 PhoTocera texana, the ichneumons Temelucha smuatus and Chelonus electus, 

 and the chalcid Brachymeria {Pseudobrachymeria) pedalis. 



OLYCELLA Dyar 



This genus is restricted in distribution to tlie United States and Mexico. 

 The larvae are white with broad transverse bands which are generally 

 dark blue or blue-black; the color intensifies in the later stages, and 

 the full-grown larvae are strikingly handsome. In 0. subumbrella 

 (Dyar), the bands are a light purple and are frequently so pale that 

 the larva appears almost wholly white. The eggs are deposited in 

 short sticks, containing from 3 or 4 to a maximum of 30 eggs. The 

 larvae are gregarious in the early stages but are solitary for the greater 

 part of their development. The host plants are various Platyopuntias; 

 other cacti have not been recorded as food plants. 



Heinrich recognises three species and one rather doubtful subspecies: 

 0. junctolineella (Hulst) from southern Texas, 0. subumbrella (Dyar) 

 from western United States, 0. nephelepasa (Dyar) from the Central 

 Plateau of Mexico, and 0. junctolineella pectinatella (Hampson) from 

 Vera Cruz. The Board's officers have encountered Olycella larvae 

 over the major portion of the western half of the United States and 

 throughout Mexico. However, as adults were not obtained from 

 material found in California, the west coast of Mexico, and southern 

 Mexico, identity was not established in these cases. The three recog- 

 nized species are characterized as follows: 



0. junctolineella. Southern Texas and northeastern Mexico. Lar- 

 vae banded with dark blue; they close the entrance to the feeding 

 tunnels. Two generations annually. 



0. nephelepasa. Central Plateau of Mexico; moths darker and rather 

 larger than those of preceding species, and the eggs are definitely 

 larger. The dark cross bands of the larvae are wider; entrance to larval 

 tunnel is not kept open. Apparently two generations a year. 



0. subumbrella. West Texas to Arizona, north to Nebraska; moths 

 dark. Larvae with pale purplish bands; the entrance to the feeding 

 tunnel is kept open for the discharge of frass. One annual generation. 

 The undetermined forms are as follows: 



Larvae with pale-blue bands, occurring in southern Mexico in the 

 States of Puebla, Guerrero, and Oaxaca. These may represent 0. 

 junctolineella pectinatella. 



