188 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



The recovery of Schedius under any conditions at all was con- 

 sidered as sufficient to justify the repetition of the rearing work of the 

 winter before, and accordingly, using a few individuals secured from 

 the field early in the fall, a series of generations has been reared in the 

 laboratory until the number now on hand (Jan. 1, 1911) runs into the 

 hundreds of thousands. In the spring it is planned to establish one 

 or two exceedingly large new colonies, sufficiently far distant from 

 any of the others to make the recovery of the parasite elsewhere a 

 certain indication that it is able to pass the winter in New England 

 and thereby justify the labors which have been expended in its 

 behalf. 



THE PARASITES OF THE GIPSY-MOTH CATERPILLARS. 

 APPARENTLY UNIMPORTANT HYMENOPTEROUS PARASITES. 



It would be presumption to state without qualification that the 

 parasites which are here brought together as unimportant are in 

 reality that. It may well be that among them are some which will 

 be of sufficient promise to make advisable the trouble and expense 

 incident to an attempt to transplant them to America, and which will 

 serve to fill in the gap in the sequence which the apparent failure of 

 Apanteles fulvipes has left. To determine more definitely their 

 relative importance abroad is one of the objects of the work for the 

 season of 1911, as at present planned, and something more than is 

 known now is certain to be known a year from now unless the plans 

 for the season go wrong from the beginning. 



The various species coming in this category are called unimportant 

 because they have never been received in imported material in 

 numbers sufficient to make colonization in America possible, and only 

 upon very rare occasions and in the instance of a few amongst them 

 only, in numbers sufficient to indicate that they were of any impor- 

 tance whatever in effecting the control of their host abroad. 



The investigations into the parasites and parasitism of various 

 native insects more or less similar in one respect or another to the 

 gipsy moth have served to throw considerable light upon the status 

 of such parasites as these. It has been shown, in the instance of 

 the tussock moth, that a parasite may be entirely absent in localities 

 where the host is abundant, or else very rare under such circumstances 

 and yet be sufficiently common to effect an appreciable amount of 

 control in localities where the host is very rare. It is thus possible 

 that some among these species may play a very important role in 

 keeping its host, when already reduced to relatively small numbers, 

 from increasing sufficiently to become of economic importance, and 

 that at the same time they may play no part at all in reducing that 

 insect from a state of or approaching noxious abundance to within 

 its ordinary limits. 



