CACTUS-FEEDING INSECTS AND MITES 111 



A coleopterous parasite, Bothrideres cadophagi, has been reared from 

 the cocoons, the adults emerging in April. 



Cactophagus spinolae var. validus LeConte 



A uniformly dull-black beetle, C. spinolae var. validus is found in southern 

 Arizona and southern California and along the Pacific coast of Mexico 

 as far south as the State of Sinaloa. In California adults have been 

 taken sparingly in June and July at Oceanside, San Diego, and the 

 Coachella Valley. In Arizona beetles have been collected in June, 

 July, and August at Oracle, Globe, and the foothills and lower valleys 

 of the Santa Rita, Quinlan, Huachuca, and Tumacacori Mountains. 

 Although fairly widely distributed in the southern portion of Arizona, 

 the insect does not appear to be prevalent in any locality ; it favors the 

 foothills and lower valleys of the various ranges and has not been 

 observed among the extensive cactus belts of the open mesa country. 



In contrast to the lightness of its population in California and Arizona, 

 this species would seem to occur in considerable numbers in the Mexi- 

 can State of Sinaloa. In August 1926 larvae were very abundant at 

 Mazatlan and Culiacan, where they were causing considerable de- 

 struction to prickly pears, including the low-growing Opuntia decumbens 

 and the much larger 0. wilcoxii and 0. fuliginosa; frequently seven or 

 eight larvae infested one segment; many plants of 0. decumbens were 

 completely destroyed by the attack. The insect was again prevalent 

 at Mazatlan in December 1933. 



The record host plants are Platyopuntias of various types. However, 

 adults have been captured in Arizona on the Cylindropuntia 0. 

 splnosior. 



Observations on the life history, made under cage conditions at 

 Uvalde, Texas, indicated an annual generation. Beetles collected in 

 the field in July fed and mated freely until December, hibernated 

 during January to March, and died in April. They laid eggs in July 

 and August; the larvae developed irregularly, many being almost 

 fully grown within six months; in April, cocoons contained pupae and 

 unpupated larvae; the adults emerged in May and June, after a life 

 cycle of approximately ten months. 



The adults hide during the day among debris at the base of the 

 plants: they become active toward dusk and feed by puncturing the 

 fruit and the younger segments* the eggs are laid singly just beneath 

 the cuticle near the base of both the more apical and basal segments. 

 The larvae tunnel freely from one segment to another, usually working 

 downward toward the base of the plant. 



