LETTER OP TRANSMITTAL 
United States Department of Agriculture, 
Division of Entomology, 
Washington, D. C, April 10, 1900. 
. Sir: I have the honor to submit for publication No. 8 of the tech- 
nical series of bulletins of this Division. It contains two articles, the 
one prepared by Mr. A. L. Quaintance, biologist and horticulturist, 
Georgia Agricultural Experiment Station, and the other, at the writer's 
suggestion, by Mr. Nathan Banks, of this Division. The subjects con- 
sidered, namely, the so-called white flies (Family Aleurodidae) and the 
so-called red spiders (the Acarid genera Tetranychus and Stigmseus), 
are both groups of very considerable economic importance, some of 
the white flies doing considerable damage to Southern horticulture, 
and the red spiders being known as greenhouse pests in all parts of 
the country and as outdoor enemies to certain crops in the warmer 
States. With these groups, as with the others which have been pre- 
viously treated in a monographic way in the earlier bulletins of this 
series, there has existed, up to the present time, so much confusion 
as to the differentiation of forms that the economic worker has not 
been able to know with any certainty the exact form upon which he 
might happen to be at work from the remedial standpoint. It is 
hoped that these papers will clear the field so that this uncertainty 
need no longer exist. 
Respectfully, 
L. O. Howard, 
Entomologist. 
Hon. James Wilson, 
Secretary of Agriculture. 
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