946 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
was positive, indicative of secondary parasitism, because every little 
while the Monodontomerus would issue from tachinid puparia which 
had been sorted out from the cocoons and pupe. Still more fre- 
quently it was reared from puparia of sarcophagids. 
In the summer of 1908 the shipment of gipsy-moth pupe from 
Italy, which served the purpose of establishing the status of the 
European species of Chalcis in their relation to the gipsy-moth, 
served also in establishing the status of Monodontomerus as a primary 
parasite of this host. A large number of the pup which were 
examined was found filled with the larve (fig. 53) or pupe (figs. 
54, 55) of the parasite, and even when the larve were still immature 
and feeding there was absolutely no trace of any other parasite present 
in the majority of instances. There was such trace in a few, and it 
was found that the former presence of Pimpla, Theronia, or any 
tachinid was very easy of determination, no matter how completely 
it might have been destroyed. 
It was felt that a mistake had been made in not liberating the very 
large number of Monodontomerus which had been secured through 
the earlier shipments, and it was resolved to colonize them as fast as 
they were secured in the future. Hardly anything was less expected 
than that the species should even then be established. 
Each winter since that of 1906-7 (Pl. X XJ) large numbers of the 
winter nests of the brown-tail moth had been collected in a vain 
endeavor to secure evidences of the establishment of Pteromalus 
egregius, but without results. In the winter of 1908—9 this work was 
undertaken anew, and almost the first lot which was brought into the 
laboratory was shortly productive of a number of Monodontomerus, 
exactly as lots collected in the open in Europe had been productive 
of the species each season since their importation had been begun. 
The circumstance, surprising and unexpected, was also gratifying, 
coming as it did so soon after the investigations which had served to 
demonstrate the primary parasitism of the species. The surprise and 
eratification was increased materially when 1t was discovered, through 
the collection of a large quantity of the winter webs, that the parasite 
was distributed over a considerable territory dicated by the area I 
on the accompanying map (PI. XXII), and though the actual number 
recovered was small, the rapid rate of dispersion was suflicient to 
indicate a very rapid rate of increase. It was estimated, in fact, that 
at least a 25-fold per year increase and a 10-mile per year dispersion 
had followed the colonization three years before. 
In 1909 an examination of the pupe of the gipsy moth in the field 
revealed the presence of what was actually a small, but under the cir- 
cumstances a gratifyingly large, number which contained the larve or 
pupe of the parasite, and the results of the winter scouting work were 
awaited with confidence and interest. They were quite as.satisfac- 
