Baltimore, October 16, 1875. 



Dear Sir : Permit nie to express my thauks for your many courtesies 

 exteuded to me while I have beeu engaged in the delicate task of dis- 

 criminating the forms of Hemiptera acquired by your surveys. It has 

 seemed important to have a complete list of all the descrilbed species 

 belonging to the regions west of the Mississippi Valley, to enable the 

 rapidly-increasing number of western students to become acquainted 

 with the work that has been done by those who have preceded them, 

 and to furnish the preliminary means for an accurate acquaintance with 

 the forms of life essential to the various localities. Accordingly I have 

 given here a summary, as complete as possible, of all the Heteroptera 

 known to occur in those regions. I have also included descriptions of 

 the new species which have beeu brought home by your expeditions. In 

 each case, the synonymy, references, and habitats have been supplied as 

 far as they are known. 



A large amount of labor yet remains to be done in securing the gen- 

 era and species characteristic of and illustrating each life area in this 

 vast territory. And it is to your enlightened enterprise that we must 

 look for the information and discriminating aggregation of the materials 

 necessary for the proper understanding of their meaning and history. 

 The present time, as you know so well, is peculiarly the proper one to 

 make extensive collections of the insects, «&c., of the great Eocky 

 Mountain system and its dependencies. The present may be the only 

 time when it will be possible to obtain the forms of life truly representa- 

 tive of the areas of distribution, either as to their local associations in 

 the development of the locality in the recent period, or as forming an 

 integral part of the geological past. 



1^0 sooner has the agency' of man impressed itself upon the natural 

 characteristics of the country, than a host of changes becomes percepti- 

 ble, and features which were before clear and stable become indistinct, 

 or are completely blotted out and lost beyond recovery. New forms of 

 life are thus made to take the place of a former fauna, and the condi- 

 tions of surrounding existence are bent to the artificial status of man's 

 requirements. 



The older parts of our country are to-day lamentable instances of the 

 artificial stamp which man impresses upon wild nature. Destruction of 

 the vegetation and of animal life takes place on every side; and instead 

 of a harmonizing and softening of the rougher features of creation, we 

 see a blotting-out and reckless change. By these unfortunate disturb- 

 ances of the balance of representative peculiarities, it has become im- 

 possible, in some parts of our Eastern States, to know what were the 

 original inhabitants of the natural areas, and what was their agency in 

 determining some of the conditions of soil and surface which we observe 

 to-day. 



To show whence the present forms of life have been derived, both 



