Chief of the Bureau of Entomology . WASHINGTON: GOVERNMENT PRINTING OFFICE. 1911. LETTER OF TRANSMITTAL U. S. Department of Agriculture , Bureau of Entomology ,      Washington, D. C, May 23, 1911 . Sir : I have the honor to transmit for publication a paper dealing with the subject of the house fly or typhoid fly. Previous publications of this department concerning this insect have been in circular form, but it is desired to make this information more widely available through the medium of a Far