INTRODUCTION. 
Probably there is no state in the Union offering a richer 
field for the student of natural history than Colorado, 
whether it be in the line of mineralogy, paleontology, zo¬ 
ology, or botany. Its broad stretch of arid plains crossed by 
streams of living water, its high mountain ranges, broad 
plateaus, innumerable gulches and deep canons, all combine 
to give it a most exceptional topography with a consequent 
diversified fauna and flora. 
The macro-lepidoptera of the state are very largely known, 
as a result of the extended collecting of Keakirt, Mead, Bruce, 
Snow and others. Lists of Coleoptera have been published 
from the collections of LeConte, Schwarz, Wickham, Snow 
and others. Lists of the Hymenoptera have been published 
by Cresson and Ashmead. But never before in any one 
publication has the attempt been made to list the Hemiptera 
of the state. Indeed, heretofore there have been no large col¬ 
lections of the Colorado species of this order to draw upon. 
During the past four years we have collected nearly all those 
previously known from the state and a very large number 
of additional forms. It has been our plan to make more than 
a simple record of the species known to occur in. the state. 
With each species is given the bibliography of all published 
records of its occurence in the state so far as known to us, 
also the name of the collector, locality, date of collection, 
and, wherever we have been able to ascertain it, the food- 
plant. Except in the case of Uhler, the authority for the 
determination of our specimens is given in the same line 
with the name. To avoid the repetition of the titles of 
papers, a numbered list of the papers referred to is given, the 
