THE BIOLOGY OF THE CHRYSOPIDAE? 
Rocer C. Smiru 
The insects included in the family Chrysopidae are of particular 
interest, first, because of their economic importance in destroying 
various small, soft-bodied noxious insects, spiders, and mites, and sec- 
ondly, because of certain phases of their life history. Approximately 
sixty species of Chrysopidae have been designated in the United States. 
Several species in each locality can well be included in the list of common 
insects. They comprise one of the most homogenous families in habits 
and morphology to be found among insects. 
The work herein described is based on the study of some fifteen species 
and covers a period of more than four years. The greater part of the 
work was done at Ithaca, New York, and additional collections and 
studies were made at Dayton, Ohio, at Milwaukee, Wisconsin, at Char- 
lottesville, Virginia, and at Manhattan, Kansas. Through the courtesy 
of Dr. Nathan Banks, the writer was permitted to study the chrysopid 
types of Hagen, Fitch, and Banks now in the Museum of Comparative 
Zoology at Cambridge, Massachusetts. 
Acknowledgment is made to Professor James G. Needham, of Cornell 
University, under whose direction this work was done. Further 
acknowledgment is made to Professor William A. Riley and to Mrs. 
R. C. Smith. 
HISTORY OF THE FAMILY 
Réaumur (1737) gave the first general discussion of this family, along 
with a discussion of the Hemerobiidae. This included a brief account 
of the habits, and a description, of three kinds of larvae. Linnaeus 
(1758) grouped the Chrysopidae with the Hemerobiidae under the name 
of the latter in his tenth edition of the Systema Naturae. The systematic 
position of the family remained unchanged until 1815, when Leach 
designated the family Chrysopidae, with the one genus Chrysopa, the 
name being derived according to Schneider (1851) from Hemerobius 
chrysopis. 
Schneider’s excellent monograph marked the real beginning of 
the modern classification of the family. From that time to the 
present, many species have been described by Brauer, Hagen, McLachlan, 
Petersen, and Navas. 
In the United States, among the early writers was Fitch (1855), who 
gave a very excellent account of the Chrysopidae. He discussed the 
life history and biology of the species in New York State, and described 
all the species he could find. Hagen (1861) listed and described thirty- 
1Also presented to the Faculty of the Graduate School of Cornell University, June, 
1917, as a major thesis in partial fulfillment of the requirements for the degree of 
doctor of philosophy. 
1291 
