LETTER OF TRANSMITTAL. 
U. S. Department of Agriculture, 
Bureau of Entomology, 
Washington, D. C, August 11+, 1912, 
Sir : I have the honor to transmit herewith for publication as Tech- 
nical Series No. 27, Part I, of this bureau a manuscript dealing with 
the insects of the family Aleyrodidse, or white flies. This family in- 
cludes several species of insects of the greatest economic importance, 
and other species are attracting attention by reason of their increas- 
ing abundance and injuries. The bureau is therefore frequently 
called upon to determine these insects, not only from this country 
but from many parts of the world. This family has been much 
neglected by entomologists and there has thus not been established a 
system of classification for the various forms. It is the aim of the 
present paper to furnish this needed system of classification, which, 
it is believed, will be found most useful to those interested in the 
family. Part II will contain an account of the species of the large 
and important genus Aleyrodes and will complete the monograph of 
the family. 
Respectfully, L. O. Howard, 
Entomologist and Chief of Bureau. 
Hon. James Wilson, 
Secretary of Agriculture. 
m 
