20 Annals Entomological Society of America [Vol. VI, 



to note the action and peculiarity of each color when tested. 

 Accidental rupture of the abdomen of a mosquito, thus extruding 

 the contained blood, should cause no confusion as this blood 

 does not diffuse as does a stain, and furthermore, after a few 

 minutes in the solution, it turns brown. If a spectroscope is. 

 available, all colors recovered should be confirmed. As a pre- 

 caution, all tested mosquitos should be destroyed daily. It is 

 advisable that each day's catch be examined as soon as possi- 

 ble, and whenever delay is necessary, afford protection from ants. 



SUMMARY. 



1. It is essential, first of all, to have a good map of the 

 territory, to keep a record of climatic conditions, to know the 

 topography and plant associations, the species of mosquitos 

 studied, etc. 



2. Larvce and pupae must be collected in large numbers, 

 cared for at a field laboratory and the adults that emerge kept 

 in first class condition until ready to be colored and released. 



3. These adults must be stained lightly and carefully, 

 without injury to the insect, and the stain allowed to dry on 

 the mosquitos before they are released. Color at liberating 

 station. 



4. Release the adults, noting conditions under which this 

 is done. Brush your clothing. 



5. Collect daily as with a fine comb, the mosquitos that 

 entered the buildings, tents, and traps. Test these for any 

 color present. 



6. Lastly, interpret rightly your results. 



ACKNOWLEDGMENTS. 



The writer is particularly indebted to Colonel W. C. Gorgas, 

 Chief Sanitary Officer, Isthmian Canal Commission, for permis- 

 sion to contribute and publish this paper. 



He also extends his gratitude to the following gentlemen 

 who favored him in many ways: Mr. J. A. Le Prince, Chief 

 Sanitary Inspector; Dr. A. J. Orenstein, Assistant Chief Sani- 

 tary Inspector; Dr. S. T. Darling, Chief, Board of Health 

 Laboratory, Ancon Hospital; Messrs. A. R. Proctor, C. H. 

 Bath, J. B. Shropshire, W. S. Chidester and Geo. Parker, 

 Sanitary Inspectors. 



November 25, 1912. 



