Fio 



Photo,, Bureau of 'Entomology, Dept, Agriculture, U.S.A. 

 54 — Transverse section of a fruit of 0. eruielmanni sliowing tlie burrows and pupa-cases of a Ocidomyua 

 fly regarded as Asphnndylla opu)ifuE. Note the destruction of the seeds. (See ahn Fig. 53.) 



Fi 



g. 55. A spineless Opuntia— C. /icw.-u. -/if a -showing the presence of galls at the aicoles, the galls being 

 caused by the larva of a Cecidomyiid fij^Itonula <,puiiti.a--a very destructive enemy of prickly pears 

 in the greenhouses of the New York Botanic Gardens, where the photo, was taken. 



Fig 



50.— A view of a gall in 0. xtrrptacaiitlia. 



New York Botanic Garden-.. 



