54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 52 



made to prove it in the case of most of the species occurring in the 

 Canal Zone. One of the species, Anopheles eiscni, has an abnormal 

 life history. It breeds in tree-holes and similar places instead of open 

 puddles. It is quite possible that this species is not infectious ; but 

 it is most important for the practical work that this should be in- 

 vestigated, as the usual methods of destruction by drainage and oil- 

 ing of the ponds does not affect this species. 



Another large group of mosquitoes not affected by the present 

 methods are those breeding in the parasitic plants high up in the 

 branches of trees. None of these are supposed to carry disease/ 

 though it might be rash to take this for granted, with our present 

 limited knowledge about them. At all events, the species of the 

 genus Wyeouiyia, which almost exclusively breed in such places, are 

 among the few day-biting mosquitoes and are decidedly noxious, 

 where they abound, as in the case of Wyeomyia adclpJia around the 

 I. C. C. Hotel in Tabernilla. 



It might be difficult to arrange the work of extermination so as 

 not to destroy the predaceous, and therefore beneficial, species of 

 Megarhinus, Psorophora and Littda; in fact, this discrimination 

 would be somewhat doubtfully warranted, as some of these are them- 

 selves aggressive biters. Some mosquitoes are known not to bite 

 man, as the true crab-hole mosquito of the genus Dcinocerites. The 

 tedious and at best uncertain work of oiling these numerous holes, as 

 it is now done, might be saved if it were definitely ascertained, as it 

 is reasonable to suppose, that the other crab-hole-inhabiting species 

 also are harmless. 



It would seem within the scope of the work of the Sanitary De- 

 partment to utilize the unique opportunities on the Zone to work out 

 some of the hundreds of problems of a similar nature which must be 

 solved before our knowledge of these insects, so intimately connected 

 with human welfare, is complete. With easy access to abundant 

 material of many species of mosquitoes, now that the life histories of 

 most of them have been studied ; with the constant influx of malarial 

 patients in the hospitals available for observation and experimenta- 

 tion, and with the large staff of medical men, among whom talents 

 for bacteriological and systematic scientific work can not be wanting, 

 the Sanitary Department on the Canal Zone has great opportunities 

 to acquire knowledge which can not be gained except on the spot, 

 and thus contribute this nation's full share in the solution of the 

 world's problems in this important part of tropical medicine. 



Such knowledge, though in its nature merely theoretical and i)urely 

 scientific, would be of great practical value and would alone enable 



* See footnote page 98. 



