IOWA ACADEMY OF SCIENCES 
173 
the food plants for each species, especially in the larval stages. 
Third, the collection of all species occurring on grasses and 
their careful identification with a close study of the specific lim* 
its of each, as a basis for further life history studies. 
Any facts suggestive of successful treatment have been care- 
fully noted, and suggestions as to treatment of individual spe- 
cies made, but it has been deemed essential in this study to hold 
in reserve general conclusions as to treatment and to gather, 
first, all facts possible bearing on the life and habits of the 
species. These will undoubtedly furnish a scientific basis for 
economic treatment. 
Insectary studies have consisted in rearing, as far as possible, 
all species in breeding cages, consisting of glass globes or netted 
frames over grass in large pots, along with continuous field 
study, the one as check to the other. In the investigation some 
sixty species have come under observation as grass feeders, 
not to mention some sixty more referred to other food plants, 
and their study has involved the examination of many thousands 
of individuals in all stages 
Of a number of species we are able to present sufficient 
details of life history to warrant positive conclusions, while of 
others the record is yet too fragmentary to be more than a 
starting point for future work. 
While this study was undertaken primarily with reference to its eco- 
nomic aspects, and this phase has been dealt with particularly in a paper, 
duplicating this in part, to be published in bulletin 34 of the Iowa experi- 
ment station, so much matter of a technical nature has been accumulated 
which seems of importance in the systematic study of this group that it 
has been deemed desirable to publish it, with full technical descriptions of 
new species, where it will reach students of systematic entomology, and 
those interested in the biological questions discussed. 
We have as a basis for work in this group, aside from the large mass of 
material collected in Iowa, types of all the Homoptera described by Mr. E. 
P. VanDuzee as well as the entire collection of Hemiptera which he made, 
and which formed the basis for his numerous contributions to American 
Hemipterology. 
The college collections contain, further, a large amount of material in 
Hemiptera from Colorado, South Carolina and Georgia collected by Morri- 
son; from New Mexico, Arizona, California and the northwest, collected by 
Wickham; from Mexico, collected by Osborn and Townsend, besides numer- 
ous smaller series received, in exchange or for determination. Also series 
of European species, embracing representatives of a large proportion of 
the genera. Also some exotic material from the Bahamas, West Indies, etc. 
The plates are photo-reproductions of drawings made by Miss Charlotte 
M. King, under personal direction and supervision of the authors. 
It has not been our purpose to prepare a full list of species, but only 
to include such as we have studied. We have followed in arrangement, 
however, the “Catalogue of Ja?soidea,” by Mr. E. P. VanDuzee, and that 
catalogue may be consulted for additional references, synonomy and bib- 
liography. 
Types of the new species are deposited in the National museum. 
