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 sj-Bcies 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 sjstematic 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 Jassoidea," 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. 



