June, '13] TOWNSEND: COTTON SCALE 323 



Of the fifteen enemies enumerated as now at work on the piojo 

 bianco in Piura, probably the most effective at present is the small 

 black coccinellid beetle, Microweisia (?) sp. Next to it in present 

 effectiveness evidently come Aspidiotiphagiis and Arrhenophagus. 



Enemy Work for the Future 



It is desirable that further enemies be imported, especially with 

 the view of finding if possible one or more kinds that will continue 

 high activity through the dry season in Piura. The most promising 

 regions in which to search for such enemies are Sonora, Sinaloa and 

 especially the Gulf coast of Lower California; also probably parts 

 of western Australia and western Africa. Arid region coccinellids 

 should be especially searched for and tried. The most promising re- 

 stricted district that can at present be suggested for such search is 

 on the Gulf coast of Lower California near the middle of the penin- 

 sula, opposite the Sonoran port of Guaymas and between the two 

 settlements of Santa Gertrudis and Santa Rosalia. Of the whole 

 peninsular of Lower California, noted as a land of drought and desert, 

 this district receives the least rainfall and has the highest temper- 

 atures, with the minimum of atmospheric humidity during the year. 

 Its coccinellids should therefore be able to continue activity through 

 the Piura dry season. The drj-est and hottest regions of western 

 Australia should also be searched for scale-feeding coccinellids. All 

 importations from excessively arid regions should be so timed as to 

 arrive in Piura in December and Januar^^ This applies regardless of 

 Avhether they come from points in the northern or southern hemisphere. 



Present experience does not warrant further introductions into 

 Piura of enemies from humid regions, except perhaps in the case of 

 the coccidivorous fungi that have proved so successful against scale- 

 insects in Florida. These fungi would probably flourish in Piura 

 during the humid months, and might very materially decrease the 

 number of the young scales that escape the present enemies. All im- 

 portations from regions more humid than Piura should be so timed 

 as to arrive in Piura during June and July. 



Artificial breeding in the insectary of the three coccinellids now 

 attacking the scale in Piura, Microweisia (?) sp., PsyUobora sp., and 

 Exochomus sp., should be extensively pursued, especially with the 

 first, during the months of August, September and October, for the 

 purpose of producing as large quantities as possible for distribution, 

 and such breeding should be continued through the dry season in 

 the insectary by artificially supplying the reciuisite degree of atmos- 

 pheric humidity. Distributions of these coccinellids should be made 

 continually over the infested region during November and through 



