334 J- T - PATTERSON. 



statement on this point, limiting the account almost entirely to 

 the species with which the paper deals. 



The general features of polyembryony in insects have been 

 given in the well-known papers of Marchal ('98, '04) and Sil- 

 verstri ('06, '08), but there are many points concerning the 

 details of this process which have not as yet been worked out. 

 It was with the view of studying certain of these details that led 

 the writer three years ago to seek an American species upon 

 which such studies could be made. Dr. L. O. Howard 1 suggested 

 that Copidosoma gelechiiz, which parasitizes the larvae of the 

 Solidago gall moth, Gnorimo schema gallcesolidaginis, would be 

 a good form upon which to work, as it seemed to be an undoubted 

 case of polyembryony. 



The Gnorimoschema moth makes the ellipsoidal galls on the 

 stems of several species of goldenrod. Baron Osten Sacken ('63) 

 seems to have been the first to have published a description of 

 the inflated carcass of the Gnorimoschema larva, caused by the 

 chalcis parasite; but apparently he was not acquainted with 

 the maker of the gall. In 1869 in connection with his account 

 on the life history of this moth, Riley states that the caterpillar 

 serves as a host for no less than six different species of hymenop- 

 terous parasites. One of these, which is shown in his Fig. 6, 

 Plate 2, is described as a "little fly of a dark metallic green color, 

 with reddish legs." This is clearly Copidosoma. Riley states 

 that the larvae of this species infests the caterpillar in great 

 numbers, more than 150 having been obtained from a single host. 

 He supposed that the "mother fly" gnawed a passage through 

 the gall and desposited her batch of eggs in the inmate. He 

 pointed out that the larval parasites cause the caterpillar to 

 swell to three or four times its natural size, and after having 

 absorbed all the juices of the victim, form very small brownish 

 cocoons, which are so packed together that they give to the worm 

 the puffed-up appearance which is typical of the mummified 

 carcasses of lepidopterous larvae that have been parasitized by a 

 polyembryonic species. It was this inflated condition of the 

 larval host that led Riley to call the parasite the " Inflating Chalcis 



1 For this as well as for other suggestions received throughout the progress of 

 the work, the writer is greatly indebted to Dr. Howard. 



