48 ENTOMOLOGICAL SOCIETY 



Mr. Schwarz added some remarks on the insects living on 

 mesquite (Prosopis juliflora} and cactus {Opuntia engel- 

 manni} in southwestern Texas. The mesquite is abundant 

 throughout the lower Sonoran region, but the insect fauna peculiar 

 to this plant is much richer in species in southwestern Texas than in 

 New Mexico, Arizona, and further west. With Opuntia engel- 

 manni the same may be observed, the range of the plant being 

 not identical with that of the insects living upon it. Among the 

 mesquite insects, two species are extremely abundant and of especial 

 economic importance, viz., Chrysobothris octocola and Cyllene 

 crim'corm's,ihe\ai-vze of which are greatly destructive to the sap- 

 wood of the larger trunks when these are cut down for build 

 ing purposes or for use as fuel. The engines of the National 

 Mexican railroad use mesquite as fuel, and consequently these 

 tw r o beetles, with their numerous parasites and other insect ene 

 mies and inquilines, are constantly carried from Mexico into Texas, 

 and vice versa. Of the Opuntia insects, the most important are 

 the larvae of Monilema working underground in the roots, the 

 most abundant species being a race of M. crassum. Clumps of 

 plants infested by them can at once be recognized from their 

 stunted growth. Above ground the stems are sometimes de 

 stroyed by a combined attack of certain Diptera and Coleoptera. 

 An undescribed little Ortalid fly breeds in the stems, apparently 

 without injury to the plant, but after the flies have emerged the 

 small cavities wherein they developed are used by two species 

 of Acalles (nobilis and turbidus} for oviposition. Their larvae 

 considerably enlarge the cavities, and after they have finished 

 their transformation the stems are occupied by the larvae of the 

 Syrphid Copestylum marginaium, which convert the interior of 

 the stem into a badly-smelling fluid. 



