LETTER OF TRANSMITTAL. 
United States Department of Agriculture, 
Division of ENTOMOLOGY", 
Washington,- D. C, April 20, 1S97. 
Sin: I have the lionor to Btibmit for publication the accompanying technical bul- 
letin, which it is hoped will enable all entomologists as well as all other persons who 
have access to a compound microscope to distinguish definitely between the San .lose 
scale and its closest allies. This bulletin has been prepared under your authoriza- 
tion by Prof. T. D. A. Cockerel], whose long technical study of the scale insects has 
especially fitted him for the work. Although the specific characters of the San Jose 
scale have been given in a number of different publications, they have not been dis- 
played by exact contrast to those of the most closely allied species, and it has resulted 
that almost allot the entomologists in the United States have felt themselves unable 
to decide authoritatively as to the identity of suspected forms, and have always for- 
warded specimens either to this oltice or Professor Cockerell in New Mexico for cer- 
tain determination. Jt is the hope and expectation of the author of the bulletin and 
of the writer that by the aid of this account of the insect and its allies all of this 
uncertainty will be done away with and that much valuable time will be saved. 
Respectfully, 
L. O. Howard, 
Hon. James Wilson, Entomologist. 
Secretary of Agriculture. 
CONTENTS. 
Page. 
The preliminary examination 3 
The study of the scale 4 
The microscopic characteristics of the adult females 5 
The subgenera and sections of Aspidiotus 9 
The relationships of the 8an Josse scale 14 
Habits of the species 16 
Annotated list of the species of Aspidiotus 18 
Postscript 31 
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