22 BULLETIN 1028, U. S. DEPARTMENT OF AGRICULTURE. 
Often the parasite is recovered the year following colonization. 
A. melanoscelus has been recovered from all but one of the colonies 
liberated previous to 1918. It has been recovered from half of the 
colonies put out in 1918 and from both of the colonies liberated in 
1919. Recoveries of the parasite were made late in the summer of 
1920 in a few of the towns which were colonized during June of that \ 
year. 
DISPERSION. 
The inner black line on the map (PI. IV) shows the present known 
distribution of the parasite in New England, it having been recovered 
from practically every town within this line. It is probable that in 
some cases A. melanoscelus has spread beyond the line indicated, for 
many of the towns just outside of the dispersion line have not been 
scouted. 
It is rather difficult to determine the exact distance the parasite ( 
will spread in a year, for when the parasite is scarce its recovery is 
largely a matter of chance. The number of host larvae which it is 
practical to collect in an endeavor to rear the parasite for disper- 
sion records is infinitesimal when compared with the larvse present 
in a town. Scouting for the cocoons is more satisfactory, but this 
is not infallible, and the fact that a town may have been scouted and 
no cocoons found does not prove that the parasite is not present. 
The recovery records show that the greatest spread of this species 
has been to the north and northeast, similar to the dispersion of the 
gipsy and brown-tail moths. The data obtained indicate a spread 
of about 25 miles a year in this direction. During the summer of 
1918 there were two recoveries made which because of their loca- 
tions are of special interest. One of these recoveries was made at ( 
Provincetown, which is 25 miles northeast of Harwich, where the 
nearest colony of A. melanoscelus was liberated in 1915. The other 
recovery was made on the island of Nantucket, which is 25 miles 
south of the Harwich colony. In 1915 a colony of A. melanoscelus 
was liberated in Middleboro, about 33 miles southwest of Prov- 
incetown. The colonies at Harwich and Middleboro were the only 
ones that had been liberated in that part of the State. These recov- 
ery records can not be taken as absolute proof of a flight of 25 miles 
for the insect, as it is possible that cocoons of the parasite were taken 
to Provincetown and Nantucket on cordwood or other material. This k 
does not seem likely, however, for the parasite was not recovered from 
any of the other towns in southeastern Massachusetts until 1919. The 
number of cocoons taken at Provincetown and Nantucket in 1918 
indicated that the parasite had been present in both places for 1 year 
at least. 
