1909] GIRAULT AND SANDERS — CHALCIDOID PARASITES 119 
THE CHALCIDOID PARASITES OF THE ‘COMMON HOUSE OR 
TYPHOID FLY (MUSCA DOMESTICA LINNAEUS) AND ITS 
ALLIES. 
I. RECONSTRUCTION OF THE CHALCIDOID GENUS Nasonia ASHMEAD OF THE 
Famity PTrEROMALIDAE, WITH DESCRIPTION AND BroLtoay or Nasonia brevi- 
-cornis ASHMEAD, SPECIES NOVA, ITS TYPE SPECIES FROM ILLINOIS. 
BY A. A. GIRAULT AND GEORGE ETHELBERT SANDERS, UNIVERSITY OF ILLINOIS. 
Introduction. 
Durtnc the course of some investigations concerning the economy and biology 
of the common house, or typhoid fly as it is now being more appropriately called,— 
Musca domestica Linnaeus — carried on in the insectary of the Office of the State 
Entomologist of Hlinois in the late summer and early fall of 1908, a quite unexpected 
abundance of a number of hitherto unnoticed or little known parasites of that host 
and others of the higher Diptera occurred, among which three generic forms pre- 
dominated — Spalangia Latreille, Muscidifurax Girault and Sanders MS.1 and 
Nasonia Ashmead, all of the family Pteromalidae. The latter genus is now under 
consideration. In this paper, from a large number of specimens of both sexes, the 
genus is redescribed in detail and its type species described as new under the name 
originally given it by the late Dr. Ashmead (Ashmead, 1904). We enter into the 
status of the genus and its sole species beyond. Such biological facts as were learned 
concerning it are also incorporated herewith. 
In the series of papers to follow, the genera of the parasites met with during the 
investigation are considered in detail, and finally, a list of the Chalcidoid parasites of 
the world’s Muscideous Diptera is given, as well as a summary of the whole. 
History and Description of the Genus. 
The genus Nasonia was based on specimens collected at Algonquin, Illinois, 
in 1894 and 1895 and sent to the United States National Museum by Dr. William 
A. Nason in whose honor it was named. [t was proposed and described by Ashmead 
in 1904 (1. c.) in a table of the genera of the pteromaline tribe Eutelini and the un- 
described Nasonia brevicornis was named in connection with it as type. The 
generic description is as follows, extracting from the table: 
1 Described in the third paper of this series. 
