PARASITISM OF BROWN-TAIL MOTH IN AMERICA. 145 



CHALCIS COMPSILUR.E. 



Upon several occasions specimens of Chalcis have issued from 

 cocoons of the brown-tail moth collected in the open. The species 

 has been compared with other species of the genus by Mr. J. C. 

 Crawford, who has found it to be distinct and has described it under 

 the name Chalcis compsilursc. 



ElJPHOROCERA CLARIPENNIS MACQ. 



Several times reared from brown-tail caterpillars collected in the 

 field, but always, apparently, rare in this connection. 



Tachina mella Walk. 



Never a common parasite in connection with this host. Usually 

 about on a par with Euphorocera and without economic significance. 



Phorocera saundersii Will. 



A single specimen thus determined by Mr. Thompson was reared 

 in 1910 under circumstances which quite conclusively indicate this 

 host relationship. 



EXORISTA BOARMLE COQ. 



Like the above, only a single individual of this species has been 

 reared from brown-tail caterpillar collections, but under circumstances 

 which were not so decisive as in the last-mentioned instance. Mr. 

 Thompson is authority for this determination also. 



Undetermined Tachinid: (?) Phorocera leucanle Coq. 



One of the most remarkable instances of attack on an unsuitable 

 host by a tachinid parasite is that of the species which in the labora- 

 tory notes is always referred to as above, upon the caterpillars of the 

 brown-tail moth. The history of this species, the identity of which 

 is very much in doubt, is in certain respects comparable to that of 

 Tachina mella in its relations to the gipsy moth. As may be seen by 

 the summarized results of the rearing work in 1910 (Table VI), it 

 is not infrequently a parasite of some little consequence, and in all 

 many hundreds of its larvse have been secured from field collections 

 of brown-tail caterpillars. 



Invariably, however, these larvse died without forming perfect 

 puparia. For a long time it was thought that this was due to unfa- 

 vorable surroundings at the time when pupation was attempted and 

 62188°— Bull. 91—12 10 



