PARASITISM OF BROWN-TAIL MOTH IN AMERICA. 143 



tion to the number of pupae collected than would be the case had 

 these collections been made irrespective of the localities where the 

 species was so recently colonized. 



Parasitism by Theronia is somewhat less on the average than in 

 some other years when similar studies have been made. At times 

 it has amounted to as much as 2 per cent. 



Sarcophagids are not considered as parasites, but rather as scav- 

 engers. Their true status is yet to be determined, however. 



Compsilura concinnata is not commonly secured from the pupae, 

 and in one instance in which more than an insignificant number of 

 this species was recovered the collection consisted of caterpillars, 

 which had prepared for, but not undergone, pupation. 



No Monodontomerus were reared from any of the collections of 

 pupae included in Table IV, nor has the species ever been recovered 

 from counted lots of pupae collected in the open. It was found in 

 1910, as in 1909, by the examination of unhatched pupae after the 

 most of those remaining healthy had produced the moths, and issued 

 in unsatisfactory numbers from collections of pupae made at the same 

 time. These were not counted at the time of collection, and on that 

 account were not included in the table. 



PARASITISM OF THE BROWN-TAIL MOTH IN AMERICA. 



The brown-tail moth in America is subjected to a considerably 

 higher percentage of native parasitism than is the gipsy moth, but at 

 the same time, as will appear in the summarized results of the rearing 

 work in 1910, the aggregate is scarcely sufficient to be considered as 

 consequential. 



The following species have been reared, and doubtless the list will 

 receive additions in the near future. 



Trichogramma pretiosa Riley. 



A very considerable percentage of the egg masses collected in the 

 open is parasitized by this species, but because of the inability of 

 the parasite to attack any but the more exposed eggs in a mass, the 

 actual percentage of parasitism is insignificant. 



LlMNERIUM CLISIOCAMP^E WEED. 



In 1907 a single specimen of this common parasite of the tent 

 caterpillar was reared from a brown-tail caterpillar collected in 

 Exeter, N. H. One or two other rather doubtful records have been 

 made since. It is unquestionably not- an important parasite of the 

 brown-tail moth. 



