PABASITES OF GTPSY-MOTH PUPJE. 245 



time special efforts will be made to recover the species from the field 

 as a result of earlier colonization. 



MONODONTOMERUS ^EREUS WALK. 



Few among the parasites have been the cause of a larger variety of 

 mingled feelings than this, and the history of its introduction into 

 Massachusetts is in many respects unique and apart from similar 

 histories of the other parasites. 



The females (fig. 51) have the curious habit of hibernating in the 

 winter webs of the brown-tail moth, and the species is rather a 

 parasite of the brown-tail moth pupse than of the gipsy-moth pupse, 

 although it is sometimes common in the latter connection as well. 

 It was first received at the laboratory in the winter of 1905 in ship- 

 ments of brown-tail-moth hibernating nests and was reared from 

 these nests in the spring. It has been recorded as a parasite of the 

 gipsy moth, and a colony was planted by Mr. Titus early in the 

 spring of 1906. The records of this colony have apparently been lost 

 and it will never be known exactly how many individuals were 

 included in it. 



Some 1,700 issued from the imported nests that first spring, but 

 not all of them were liberated. Dr. W. H. Ashmead, 1 to whom the 

 specimens were sent for determination, stated it as his opinion that it 

 was a secondary parasite rather than a primary, since few or none of 

 the group to which it belonged were definitely known to be primary 

 parasites upon lepidopterous hosts. Accordingly the work of coloni- 

 zation was stopped almost as soon as it was begun, and for a period 

 of more than two years Monodontomerus was treated as a secondary 

 parasite, and destroyed whenever found. During this period, many 

 thousands issued from importations of brown-tail-moth cocoons, and 

 much doubt was felt as to its actually being a secondary, on account 

 of the numbers alone, since it enormously outnumbered all other 

 hymenopterous parasites (whether primary or secondary) reared. 

 For reasons which would be obvious to anyone who has ever had any 

 experience in handling the cocoons of the brown-tail moth, no serious 

 effort was made to determine its host relations by the dissection of 

 the brown-tail moth pupae. A few pupse were sought out from 

 which it had issued, and no trace of any other host was found, but 

 such was the state of our technical knowledge at that time as to 

 render questionable such evidence. We were not sufficiently 

 familiar with the appearance of pupa3 from which Monodontomerus as 

 a secondary parasite had issued, and dared not give any more than 

 negative weight to the fact that no remains of any other primary 

 host than Monodontomerus could be found. Moreover, against this 

 negative evidence indicative of primary parasitism, was much that 



1 Now deceased. 



