CACTUS-FEEDING INSECTS AND MITES 39 



the average number being between 100 and 150. On one occasion in 

 Australia 716 females laid an average of 197 eggs per individual. 

 Thus, each female deposits many eggsticks. 



The young larvae, which are social in habit, enter the fruit and 

 young segments. Their penetration is soon followed by the decay of 

 the attacked portion; within two weeks young segments usually are 

 destroyed by a black nonliquid rot. The young larvae appear unwilling 

 or unable to escape from the rapidly decaying tissue; generally not 

 more than two or three larvae from the original colony survive this 

 early mortality. Hunter, Pratt, and Mitchell (1912) attribute the 

 scarcity of larvae to cannibalism, but the peculiar reaction of the plant 

 to the attack, a condition which does not operate in the case of the 

 entrance of young Melitara and Cactoblastis larvae, would seem to be 

 the responsible factor. 



After escaping from the original fruit or segment, the larvae adopt 

 a solitary habit. They now attack older segments, entering near the 

 apical end and tunneling straight down through the center. The 

 entrance hole is not kept open and the excrement is packed within 

 the tunnel. As the larva develops, its presence is indicated by a large 

 characteristic swelling which is partially hollow and partly filled with 

 frass and broken-down plant tissue. The swelling fills up with spongy 

 matter and may remain conspicuous for months after being vacated 

 by the larva. Not infrequently larvae die as a consequence of being 

 entrapped by the too rapid development of this tissue. The full-grown 

 larva, which attains a length of 2^2 inches, makes its exit toward tlie 

 base of the attacked segment and spins a stout white cocoon among the 

 debris. 



Many fruit and young segments are destroyed as a result of their 

 penetration by the newly hatched larvae. When the larvae become 

 solitary, however, their tunneling does not as a rule incite rot actively 

 and causes litde damage to the plant. Sometimes bacterial soft rot and 

 anthracnose fungi invade the tunnels and enlarge the scope of the 

 injury. Thus, although prevalent and often rather abundant, this 

 species is not particularly destructive. 



Parasites. — The following natural enemies have been reared from 

 the pupae : the tachinids Phorocera texana and Lespesia aletiae, the braconid 

 Apanteles sp. ; and the chalcid Brachymeria (Pseudobrachymeria) pedalis. 



Olycella nephelepasa (Dyar) 



This species was described from specimens from Techuacan in the 

 southern highlands of the State of Puebla, Mexico. Heinrich lists 

 Cuernavaca, Mexico City, Aguascalientes, and San Luis Potosi as 



