44 The Control of Mosquitoes 



shelter or harboring place for Anopheles during the 

 daytime, as well as for other mosquitoes. The 

 climatic conditions were so different from those 

 previously encountered that it was evident much 

 investigation or pioneer work was required to ob- 

 tain data pertaining to the general life history 

 and habits of Isthmian Anopheles. We had no 

 means of determining how seasonal changes would 

 affect propagation, and the available data were 

 unreliable. It was generally believed at that time 

 that all mosquitoes traveled more or less with 

 gentle air currents, but there was no positive 

 knowledge of the habits of flight, and the length 

 of flight of Anopheles, or of any other Isthmian 

 mosquito. This was yet to be determined. It 

 was not known if or how topography affected the 

 distribution of species, whether Anopheles larvae 

 thriving in small collections of water held by plants 

 were of economic importance, or whether certain 

 species were confined by fixed geographical limits. 



Dr. O. L. Howard assisted in the work in many 

 ways and furnished valuable suggestions and 

 advice. 



Important collections of available species of 

 Zone mosquitoes were made by Mr. A. Busckof 

 the Smithsonian Institute and by Mr. A. H. 

 Jennings, entomologist of the Isthmian Sanitary 



