INTRODUCTION 3 
In addition to these observers, the following individuals made volunteer col- 
lections and observations which were transmitted to Washington: Mr. G. G. 
Coghill, of Pacific University, Forest Grove, Oregon; Major William M. Black, 
U.S. Army, Panama; Mr. H. C. Weeks, Bayside, Long Island, New York; Dr. 
J. B. Smith, State Entomologist of New Jersey, New Brunswick ; New Jersey ; 
Dr. Alfredo Dugés, of Guanajuato, Mexico; Dr. J. W. Dupree and Prof. H. A. 
Morgan, of Baton Rouge, Louisiana; Dr. José H. Pazos, of San Antonio de los 
Baios, Cuba; Dr. W. E. Britton, State Entomologist, New Haven, Connecticut. 
The material brought together during 1903 was very encouraging, and many 
of the reports of the paid observers were full and contained many new contribu- 
tions to the knowledge of the early stages of mosquitoes. 
With the opening of the season 1904 it was thought best to limit the number 
of paid observers working in the manner described above, and only two were so 
employed, namely, Mrs. Maurice F. Ricker, of Big Fork, Montana, the wife of 
Professor Ricker, the head of the summer biological station at that point, and 
Mrs. Hinds, of Victoria, Texas. Dr. A. Siegrist, of Puerto Angel, Pochutla, 
Oaxaca, Mexico, was also tentatively engaged. The sanitary officials of the 
Panama Canal Commission promised assistance, and two of them were promised 
compensation for expenses incurred in collections and observations. The results 
from Panama and from Puerto Angel were, however, nil. 
The extreme importance of a most thorough knowledge of everything con- 
nected with the yellow-fewer mosquito (Aédes calopus) induced the grantee of 
the research fund during the spring and summer of 1904 to make an especial 
effort to determine its geographical distribution, and to learn as much as possible 
about its habits. In the course of another investigation he went to south Mexico 
in the spring, going as far south as Oaxaca, and studied the effect of altitude 
upon the distribution of the species from the seaboard at Vera Cruz up to 
Orizaba. The Mexican sanitary authorities were consulted, and his efforts were 
very intelligently seconded through the great courtesy especially of Dr. Eduardo 
Liceaga, the president of the Superior Board of Health of the Republic of 
Mexico. 
Beginning with the middle of June, Mr. Herbert Barber, of Washington, was 
sent upon a trip to determine, if possible, the line of northward distribution of 
the yellow-fever mosquito in the United States. He began at Brownsville, 
Texas, and followed approximately the line of distinction between the upper and 
lower austral life zones as laid down by Merriam. He proceeded gradually as 
far as Louisville, Kentucky, where the work was taken up September 1 by Mr. 
T. H. Coffin, who followed it through to the Atlantic seaboard. 
By the operations just described the main portion of the mosquito fauna of 
the principal inhabited regions of the United States was rather fully worked 
up, and during 1905 an especial effort was made to secure material representing 
the mosquito fauna of southern Mexico, Central America, the West Indies, and 
Alaska. The Canal Zone was again left to volunteer observers. One of the 
authors, Mr. Knab, left Washington the end of May, visited Key West and 
Havana, then Vera Cruz, Cérdoba, Orizaba, Santa Lucrecia, Rincon Antonio, 
Almoloya, Tehuantepec, Salina Cruz, and Acapulco in Mexico; Acajutla, San 
