LIST OF PROBABLE PARASITES. 1 
Ichneumon subcyaneus Cresson. Ichneumon ccerulens Cresson. 
Allocota (Hemiteles) thyridopterigia Riley. 
LIST OF SCAVENGERS. 
(Roared from dead chrysalidsor cocoon masses. 
Diptera. 
FTelicobia helicis Towns. Limosina sp. 
Sarcophaga Bpp. 2. . Homalomyia Bcalaria Fab. 
Phora nigricepa Loew. Gaurax anchora Loew. 
Phora iucisuralis Loew. Neoglaphyroptera bivittata say. 
Phora fasciata Pall. Diplopia sp. 
Phora agaraci Lintner. 
In addition to the insects listed above, a species of Chrysopa was 
reared from the cocoon mass, the larva' of Anthrenus varius were found 
feeding upon the dead pupae and empty egg masses, and a mite of the 
genus Tyroglyphus was found to have the same habit. 
Other active agents in the further reduction of the numbers of the 
tussock-moth caterpillars were an undetermined disease upon which 
Mr. A. F. Woods, of the Division of Vegetable Pathology, has been at 
work, and the Heteroptera Podisus sphwsus, Euschistus scrvus, and Pri- 
onidus cristatus. 
The total number of primary parasites reared in the course of the 
observations was 2,122, of which L85 were Diptera and 1,937 Ilymen- 
optera. The secondary parasites numbered about 1,000, but this is an 
estimate, as no exact account was kept of the many specimens of the 
minute Dibrachys and Asecodes. The writer deems it advisable to 
give in some detail the observations made upon each of these species 
in order before drawing general conclusions, since the basis for such 
conclusions must be the knowledge of the habits of the individual 
species involved. 2 
Pimpla inquisitor Say. 
This important and widespread parasite of lepidopterous larvae 
occurs in California, Texas, Iowa, Illinois, Missouri, Ohio, Xew York, 
and the District of Columbia, and is probably to be found in all parts 
of the United States, except possibly in boreal regions. It is parasitic 
'All observed closely investigating recently formed cocoons of the tussock moth 
and apparently about to oviposit. The third species is parasitic upon Pimpla. 
s The observations upon which the following statements are based have largely 
been made by Mr. Pergande, the assistant in charge of the insectary. Messrs. Pratt 
and Busck have also helped, and Mr. Coquillett was for a short time in charge of the 
breeding experiments during Mr. Pergande's absence. The writer made certain field 
observations in the fall of 1895 and sammer of 1896, and carefully dissected and 
examined very many Orgyia cocoons during December, 1896. The dipterous para- 
sites have been named by Mr. Corpiillett. and Mr. Ashmead has assisted in the nam- 
ing of the Hymeuoptera. 
