INTRODUCTORY. 
This paper is the result of two years’ study of the Coccidae 
in the Ohio State University Zoological Laboratory, under the 
able direetion of Prof. Herbert Osborn, who has devoted much 
time to the study of the Hemiptera, of which Order the Coccidae 
comprise a comparatively small group. 
It has been the plan of the author to arrange the paper in 
the form of an illustrated manual, furnishing keys and descrip- 
tions for the species reported in Ohio. Several species were not 
deemed sufficiently important to require an extended description 
and a figure. In the eourse of the work the author has added 
32 species to the Ohio list, including six species new to science. 
One of these (Aspidiotus glanduliferus) was deseribed by Prof. 
Cockerell, and five (Phenacoccus osborni, Chionaspis gleditsiae, 
Ch. sylvatica, Aspidiotus piceus and Orthezia solidaginis) were 
deseribed by the author. 
On account of the lack of specimens and literature at hand, 
the author omits the Coccinae in this paper except to list the re- 
corded species, hoping in another year to work up this group in 
similar manner. Any assistance in the way of specimens or 
literature will be gratefully received. 
In illustrating the Diaspinae, the author has shown on one- 
half of the drawing the dorsal, and on the other half the ventral 
surface, and has endeavored to be as accurate as possible in 
delineating the relative size and position of the gland-orifices, 
both dorsal and ventral. 
The male seale has been deseribed immediately after the 
female seaie, it seeming proper to give first the superficial charae- 
ters of each one before passing to the microscopic characters 
of either one. 
* Presented to the Faculty of the College of Arts, Philosophy and Science of the Ohio 
State University as the thesis requirement for the degree of Master of Arts. June, 1903 
Contributions from the Department of Zoology and Entomology, No. 18 
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