CACTUS-FEEDING INSECTS AND MITES 105 



Peru. One cocoon at Huanuco contained many dead pteromalid 

 chalcid parasites. 



ONYCHOBARIS LeConte 



One small cactus weevil from the United States is included in this 

 genus. 



Onychobaris mystica Casey 



The larvae of this small dark weevil feed within the segments of the 

 Cylindropuntias 0. leptocaulis in Texas and 0. fulgida in Arizona. 

 Very litde attention was paid to this insect, which causes injuries of 

 a minor nature and which does not appear to be common. 



CYLINDROCOPTURUS Heller 

 Cylindrocopturus biradiatus Champion 



A small species from Mexico which may be termed the areole weevil. 

 The larvae feed singly in cavities beneath the areoles of large prickly 

 pears, such as Opuntia streptacantha, 0. tomentosa, and 0. ficus-indica. 

 The affected areas become raised above the surface of the segments 

 and discharge a gummy secretion which hardens and renders the work 

 conspicuous. The damage is of a minor order. Larvae were observed 

 in numbers in June at Morelia, State of Michoacan, in October at 

 Guernavaca, State of Morelos, and in March near Mexico City, 

 From material collected near Mexico City, adults emerged in late 

 March, April, and June. 



Excellent figures, illustrating the various stages of the insect and the 

 nature of its attack were published by Dr. A. Dampf (1929). 



GERSTAECKERIA Champion 



Approximately 25 species of these rather small cryptorhynchid weevils 

 have been described. It would appear that all forms are cactus insects, 

 the majority being restricted to prickly pears. The distribution embraces 

 the United States, Mexico, and the West Indies. The larvae live singly 

 in cells in the cactus segments, and under normal circumstances cause 

 very litde damage to the plants. They form circular firm cocoons 

 within the cells. 



Many named species, even Texas forms, were not encountered duiing 

 the Board's investigations. However, little attention was paid to the 

 group as a whole, although studies were conducted with several species. 

 In the vicinity of Uvalde, Texas, are found four species, G. clathrata, 

 G. doddi, G. porosa, and G. nobilis. Normally the adults are active at 

 night and shelter during the day. 



