96 U.S. NATIONAL MUSEUM BULLETIN 25 6 



Studied in the United States and Mexico. Its prevalence appears 

 to be much more general and less sporadic than M. ulkei and other 

 relatively common species. For example, in May and July 1930, 

 adults w^ere abundant over a wide area for miles around San Luis 

 Potosi. 



The most northerly records of its occurrence are Durango and 

 Linares in the southern portion of Nuevo Leon, where its distribution 

 overlaps that of M. ulkei. The southern limits of its range appear to be 

 around Puebla and in the State of Morelos south of Mexico City. It 

 is particularly common around San Luis Potosi and Aguascalientes 

 and is rather prevalent in the vicinity of Mexico City. 



With the exception of the calandriid weevil Caclophagus spinolae, 

 M. variolare is the most generally destructive prickly pear insect in 

 Mexico. All forms of Platyopuntia are attacked, apparently with little 

 discrimination; the dominant semitree pear forms with thick woody 

 stems, such as 0. streptacantha and 0. hyptiacantha, are favored, as 

 well as the smaller shrub pear 0. cantabrigiensis. At San Luis Potosf 

 the Cylindropuntia 0. imbricata was freely infested but to a lesser 

 degree than Platyopuntias, Cereus plants were attacked quite ap- 

 preciably at Puebla. Obser\'ations tend to indicate that among the 

 larger prickly pears a certain amount of preference is evinced for 

 0. robusta, as compared with such other common plants as 0. strep- 

 tacantha and 0. hyptiacantha. 



The larvae feed in the branches and main stems, frequently in 

 the base of the trunk. The heavy branches of the larger prickly pears 

 often break off as a result of the injury. Large plants may crack near 

 ground level and collapse. Complete destruction of fallen branches 

 and plants usually follows, since the adults show a partiality for 

 depositing eggs on collapsed pear. 



As in the case of M. ulkei, one main and a smaller partial generation 

 are completed annually. In cage rearing work, adults emerged in 

 April and May and in September to November. General field emer- 

 gence takes place in April-May, but at Puebla beetles appeared as 

 early as February. Adults are numerous in June and July, and are 

 fairly common in October. In the cages, eggs have been laid from April 

 to June and in September and October; an incubation period of 6 

 days has been recorded in late May. The life cycle may occupy 10 to 

 12 months, but during summer development from egg to adult has 

 often been accomplished in 4 or 5 months between May and October. 

 Larvae are present in the field almost throughout the year. Some larvae 

 enter the cocoons in the autumn and produce beetles in the spring 

 montlis of April and May. A limited proportion of the autumn adults 

 survive the winter. The greatest length of life in confinement has been 



