PARASITES HIBERNATING IN BROWN-TAIL WEBS. 289 



of which came from hibernating caterpillars, but a part of which was 

 imported as parasites of the full-fed and pupating caterpillars. The 

 experiment of colonizing large numbers of retarded caterpillars in the 

 vicinity was repeated, and with similar results to those secured in the 

 previous season. 



In 1910 a larger number of the cocoons was found, but at the 

 same time a very few were secured from the caterpillars which had 

 been collected in the vicinity of the colony. It did not look as though 

 much was to be expected from the parasite at first, but when, toward 

 the end of June, collections of full-fed caterpillars were made from 

 various localities for the purpose of determining the status of the 

 tachinid parasites, the results were much more encouraging. Cocoons 

 of the second generation of Meteorus were soon found in some num- 

 bers and to a distance of a mile or more from the original colony 

 center. Within a rather limited area near the colony center they 

 could almost be said to be abundant, so abundant that 50 were col- 

 lected in the course of about two hours' work. They are far from 

 being conspicuous objects, being wholly disassociated from the cater- 

 pillar which served as host, and on this account the number collected 

 was considered to indicate a very satisfactory abundance. 



Its rate of dispersion, so far as indicated by the results of the 

 summer work upon the caterpillars of the brown-tail moth, was too 

 slow to be satisfactory, but in the early fall a single specimen, defi- 

 nitely determined by Mr. Viereck as of this species, was secured from 

 a lot of caterpillars of the white-marked tussock moth collected in 

 the city of Lynn, some 7 miles from the colony site. This would 

 indicate a rapidity of dispersion in excess of that of Compsilura, 

 and one which is distinctly satisfactory. 



Another specimen was reared in the fall of 1910 from a caterpillar 

 of the fall webworm collected in the open, and this was also con- 

 sidered as satisfactory evidence of its ability to exist here. At the 

 present time there seems to be every reason to expect that it will be 

 found in 1911 over a more considerable territory and in a much 

 greater abundance than in 1910. 



ZYGOBOTHRIA NIDICOLA TOWNS. 



The few caterpillars which Mr. Titus saved from among those 

 emerging from the hibernating nests in the spring of 1906 all died 

 before pupation, and no other parasite than Apanteles and a single 

 specimen of the Apanteles parasite, MesocJiorus pattipes, was reared 

 from them. In 1907 trouble was again experienced in carrying the 

 caterpillars from imported nests through to maturity, but among the 

 thousands which were fed in the cages at the North Saugus laboratory, 

 as described in the account of the introduction of Apanteles, a few did 



95677°— Bull. 91—11 19 



