236 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



and shipment. It is rather expected that the latter may be the true 

 explanation and that the apparent scarcity of tachinids in the para- 

 site fauna of the gipsy moth in Japan may not prove to be real. 



PARASITES OF THE GIPSY-MOTH PTJPiE. 



THE GENUS THERONIA. 



The discussion of the pupal parasites of the gipsy moth may well 

 begin with mention of the most generally distributed of all — Theronia. 

 The genus has already been the subject of brief comment in the 

 account of the American parasites, and something was said of the 

 habits of Theronia fulvescens in its relation to this host in America, 

 and of its unimportance. The form which by courtesy is thus specif- 

 ically designated is very imperfectly differentiated from T. atalantse 

 Poda, which prevails throughout Europe in relatively about the same 

 abundance in relation to the gipsy moth. It is readily distinguished 

 from the American form by its habitat and to a less satisfactory 

 extent by color. 



In Japan occurs still another, indistinguishable biologically (so far 

 as its biology is known) or morphologically, but differing in color from 

 either the American, from which it is most distinct, or from the Euro- 

 pean. It has been described as Theronia japonica Ashm. 



The role played by these so-called species in the countries to which 

 they are severally native is nearly identical and at the same time 

 unimportant, when economically considered. The likelihood that 

 either the European or the Japanese would become relatively more 

 effective in America than the American itself seems so very remote 

 as to make unworthy of consideration any serious attempts to intro- 

 duce and colonize either. Quite a good many of the European have 

 been liberated in America from time to time, but in a purely inci- 

 dental way. More will probably be received in the future and 

 similarly liberated. 



It was in the winter of 1907-8 that the late Mr. Douglas demons, 

 of the laboratory, found a large number of the females of T. fulvescens 

 congregated beneath old burlap bands in a tract of woodland in which 

 the gipsy moth was actively being fought. Some of these females 

 were dissected some days later and found to be without fully devel- 

 oped eggs, and on the basis of these inadequately conducted dissec- 

 tions it is supposed that, as in Monodontomerus, the males die in the 

 fall, leaving the females to hibernate. It would, in other words, 

 mean that the species is single-brooded. 



The subject ought to have been still further investigated, but the 

 unimportance of the species from an economic standpoint has robbed 

 it of interest other than that which has attached to the remarkable 

 and suggestive vagaries which it has exhibited in its host relations. 



