PARASITES OF GIPSY-MOTH PUP. 245 
time special efforts will be made to recover the species from the field 
as a result of earlier colonization. 
MONODONTOMERUS JEREUS 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 pupe than of the gipsy-moth pupe, 
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,' 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 pupe. A few pup 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  sufliciently 
familar with the appearance of pups 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. 
