CACTUS-FEEDING INSECTS AND MITES 109 



CACTOPHAGUS LeConte 



This purely cactus segregate of large calandriid weevils is distributed 

 from Central America to the southern border of the United States. 

 The host plants are various prickly pears of the genus Opuntia, the 

 closely allied Nopalea, and certain species of Cereiis. The only Cylin- 

 dropuntia definitely recorded as a food plant is 0. tutiicata in southern 

 Mexico, although adults were taken on one occasion on 0. spinosior 

 in Arizona. 



Four species and one variety are recognised in this publication. 

 C. validus LeConte, often considered a color variety of C. spinolae 

 (Gyllenhal) is treated as a separate species since it possesses a distinct 

 geographic distribution. On the other hand C. rubroniger Fisher is re- 

 garded merely as a color variety of C. spinolae. 



These weevils are the most destructive enemies of prickly pear in 

 Mexico. The larvae tunnel freely within the Opuntia segments and set 

 up wet-rot conditions which are enhanced by the activities of dipterous 

 scavengers and of plant diseases. Larvae pupate within the plant, 

 constructing rather bulky fibre cocoons. The adults measure three- 

 quarters of an inch to one inch in length. 



Cactophagus spinolae (Gyllenhal) 



A black beetle with two orange markings on each elytron, C spinolae 

 is the most important enemy of prickly pears in Mexico. It is dis- 

 tributed throughout the Central Plateau where its occurrence is very 

 general. The most northerly records were made at Parral in the south 

 of the State of Chihuahua, and Victoria and Palmillas in the south- 

 western section of the State of Tamaulipas. The southern limits of 

 its range appeared to be in the States of Puebla and Morelos. It was 

 extremely abundant in the neighborhood of Puebla and Tlaxcala, 

 and prevalent in areas around Mexico City. It was found in numbers 

 at Durango, Aguascalientes, and Morelia (State of Michoacan), and 

 everywhere in the State of Morelos, while it was obtained at San Luis 

 Potosi, Zacatecas, Guadalajara, Jalapa (State of Vera Cruz), and 

 many other places. 



The dominant Platyopuntias of the Mexican Plateau are tree and 

 semitree prickly pears, of which there are many species, such as Opuntia 

 streptacantha, 0. hyptiacantha, 0. lasiacantha, 0. robusta, and 0. tomentosa, 

 all of which, as well as cultivated "tunas" of the 0. ficus-indica and 

 0. megacantha types, are attacked without apparent discrimination. The 

 less common shrub prickly pears such as 0. cantabrigiensis and 0. engel- 

 mannii (at Parral in Chihuahua) are favored. In addition, diflerent 

 species of Cereus are infested freely. 



