CACTUS-FEEDING INSECTS AND MITES 85 



The dull blue-grey larvae live singly in tunnels or cell cavities, usually 

 in the terminal or subterminal segments. Frequently several inhabit 

 the same cladode. The cells are dry and clean, with exterior holes for 

 the discharge of frass. The larvae pupate nakedly within the cells. 



Apparendy there are two generations each year. The insect is in the 

 larval stage during the winter. Half grown larvae collected in March 

 were full-grown in May and produced moths in June and July. In the 

 succeeding generations the larvae were half-grown in September, 

 yielding adults in November. 



As with Metapleura potosi, this species does not cause appreciable 

 damage to prickly pear, other than the occasional destruction of 

 segments by several larvae tunneling in the same cladode. 



Lepidoptera: Tineidae 



DYOTOPASTA Busck 



Dyotopasta yumaella Kearfott 



Hunter, Pratt, and Mitchell recorded this insect as having been 

 reared from Opuntia fruit in Texas, and E. C. Van Dyke (1936) 

 states that the larvae were destroying many clumps of a small Opuntia, 

 probably 0. basilaris, in Kern County, California. 



In our experience, Dyotopasta is not a primary enemy of prickly 

 pear. Its attack is of a secondary order; the larvae have been found 

 very commonly associated with Melitara larvae in Texas, New Mexico, 

 and Arizona, occurring in the feeding cavities of these primary tun- 

 nelers and in the dried-out Opuntia segments destroyed or partially 

 destroyed by them. Dyfopasta feed mainly on the dead tissue, but appear 

 to eat to some extent the living tissue surrounding the cavities. It is 

 thought that in certain cases they have aided in the ultimate destruction 

 of the segments. 



The distribution extends southward as far as Mexico City where 

 the larvae have been observed in numbers in disused cavities in Opuntia 

 previously occupied by larvae of the moth borer Megastes cyclades, and 

 of the beetles Moneilema spp. and Archlagocheirus funestus. 



Similar larvae were noted in the dead tissue of Cereus sp. near Rio 

 de Janeiro, Brazil. 



TINEA Linnaeus, sp. 



Pink grey larvae, found in dried stems of Cereus sp, at Santa Eulalia, 

 Peru, in October 1936, produced moths in the following January. 

 This insect is probably a scavenger. 



