PARASITES HIBERNATING IN BROWN-TAIL WEBS. 277 



localities in which Pteromalus had been colonized. Several thou- 

 sands were thus collected in 1909-10 (as may be seen by reference to 

 Table X) and a much larger series of collections was planned for the 

 winter of 1910-11. 



On the face of the results of this work during the two previous 

 winters, nothing was much less likely than that Pteromalus should 

 be recovered from any of these collections of nests. When a few 

 specimens of a pteromalid which looked very much like it did issue 

 early in December, they were accorded a rather cool reception, and 

 made to identify themselves by reproducing upon hibernating catsr- 

 pillers of the brown-tail moth in confinement. Before such identi- 

 fication was complete, it was rendered unnecessary through the issuance 

 of considerable numbers of what could no longer be questioned as the 

 true Pteromalus egregius from no less than 10 lots of nests collected 

 in different towns scattered all the way from Milford, Mass., down 

 near the Rhode Island line, to Dover and Portsmouth, N. H., just 

 across the Piscataqua River from Maine. At the time of writing 

 they are still emerging from the collected nests, and the extent of 

 their dispersion is not yet known, but Mr. H. E. Smith, who is attend- 

 ing to the rearing cages, has prepared a map (Plate XXV) showing 

 the location of the original colonies as well as the towns from which 

 recovery has been made the present winter. 



Sufficient data have already been accumulated to make certain 

 the astounding fact, that as a result of the colonization work con- 

 ducted between 1906 and 1908, the parasite is now thoroughly 

 established over a territory which undoubtedly includes portions of 

 four States, and during the period of its dispersion it spread itself out 

 so thin as to make its recovery impossible except in the immediate 

 vicinity of the colony sites, and for a short period immediately fol- 

 lowing colonization. Until this time Mono don tomerus has held the 

 record for rapid dissemination, but this record is now eclipsed. 



It is impossible to determine whether the first of the colonies were 

 after all successful, or whether they actually died, as was supposed, 

 and success finally resulted from the very much larger colonies in 

 1908. If the early colonies lived, it means that no less than four 

 years elapsed before any evidence to that effect was forthcoming. 

 This fact, in its relation to circumstances attending the colonization 

 of another parasite, Apanteles fulvipes, which seems not to have 

 succeeded in establishing itself any more than Pteromalus appeared 

 to have established itself as a result of those early colonizations, will 

 sustain some hope for the ultimate recovery of this parasite until 

 1912 or 1913. 



If, on the other hand, the establishment of Pteromalus resulted 

 from the very much larger and in every way satisfactory colonizations 

 of 1908, it may mean, in its reference to Apanteles fulvipes, that very 



