Depart^ient of Agriculture, 
Bureau of Exto3iology, 
Washington, B. (7., January 9, 1885. 
Sir : One of the obstacles which the economic entomologist encoun- 
ters in this country is the impossibility of properly referring by name 
to the majority of the insect enemies and parasites of very many of the 
most prominent injurious species. This difficulty has been greatly felt 
in the work of this Bureau, and some endeavor has been made to have 
certain families, like the Tachinidse and SyrphidaB in Diptera, worked up. 
In the smaller Hymenoptera a very large amount of undescribed ma- 
terial has been reared, and as Mr. Howard has made a specialty of their 
study, I have desired that he devote whatever time he can well spare 
from his other duties, to working this material up. The paper here- 
with presented is the first of a series of descriptive papers which are 
intended to overcome the difficulty mentioned, and which, being tech- 
nical and intended for circulation among entomologists, need only be 
printed in limited edition. 
Respectfully, 
C. Y. EILEY, 
Entomologist. 
Dr. George B. Loring, 
Commissioner of Agriculture. 
