662 
Journal of Agricultural Research 
Vol. XXX, No. 7 
for the entire area an issuance of 67.2 
per cent of the Anastatus in 1922 and 
79 per cent in 1923. The laboratory 
thermograph at Melrose Highlands, 
Mass., recorded —15° F. in February, 
1922, and —13° F. in February, 1923. 
Egg clusters collected below and above 
the snow line were kept separate, and 
the issuance of Anastatus recorded. 
It was found that of the eggs collected 
in 1922 the issuance from those below 
the snow line was 90.6 per cent, from 
those above the snow line 49 per cent, 
and the average of all was 67.2 per cent. 
Of the eggs collected in 1923 the issu¬ 
ance from those below the snow line 
was 82.2 per cent, from those above the 
snow line 76.3 per cent, and the aver¬ 
age was 79 per cent. 
Among the gipsy-moth eggs from 
which these figures were obtained were 
many collected from the northern part 
of the area colonized with Anastatus. 
The average mortality of Anastatus in 
the area south of Melrose is not nearly 
so great as it is north and northwest 
of this town. There are many winters 
with practically no mortality of Anasta¬ 
tus over the eastern half of Massa¬ 
chusetts, southeastern New Hamp¬ 
shire, and southwestern Maine. 
During the spring of 1923 collections 
of gipsy-moth eggs were made from 
high land, as from the tops or near the 
tops of hills, and also from low land, as 
along the banks of rivers or brooks or 
the edge of a swamp or meadow. The 
eggs taken below the snow line and 
those from above it in each set of col¬ 
lections were kept separate. The per¬ 
centages of issuance of Anastatus were, 
for the eggs taken from the high land, 
85 for those above and 90 for those 
below the snow line, and for the eggs 
from the low land, 67 for those above 
and 88 for those below the snow line. 
The collections indicate that there is 
considerably more winter killing of 
Anastatus in the low areas than in the 
higher ones, and that the snow in 
either location offers very good pro¬ 
tection to Anastatus. 
FIELD WORK TO OBTAIN ANA¬ 
STATUS FOR COLONIZATION 
The first collections of gipsy-moth 
eggs from New England to secure 
Anastatus for further colonization work 
were made in the fall of 1909. Most 
of the eggs were collected in the vicinity 
of the centers of four of the five colonies 
which had been established in the sum¬ 
mer. Each season thereafter for some 
years collections of large numbers of 
gipsy-moth eggs were made at different 
colonies suitably located (Fig. 7, a). 
Using the exact point of liberation of 
the colony as a center, eight lines were 
run, four to the cardinal points of the 
compass and the other four intermedi¬ 
ate to them. The first year or so col¬ 
lections of gipsy-moth eggs were made 
at 25-foot, 50-foot, and 100-foot inter¬ 
vals along the lines as far out from the 
center as Anastatus was found. In 
this manner the area was determined 
where the parasitism by Anastatus was 
high enough to warrant the general 
collection of gipsy-moth eggs to obtain 
Anastatus for colonization. 
As Anastatus spread and the lines 
became longer, the greater part of the 
work was done in a colony convenient 
to the laboratory at Peabody, Mass. 
A chart of the area covered is shown in 
Figure 8. At this colony the lines were 
run farther from the center each year 
in order to determine the area from 
which to collect as many egg clusters as 
possible. General collection of eggs 
was made in the area where the eggs 
showed as high as 10 per cent para¬ 
sitism. This work was not confined to 
the Peabody area alone, but for a num¬ 
ber of years most of the material col¬ 
lected came from that area. 
Year after year these lines continued 
outward until several of them extended 
3 miles from the center. Collections of 
10 egg clusters each were made at the 
center and at intervals of 100 feet along 
the lines for 600 feet; then at intervals 
of 100 yards as far as the collections 
showed parasitism by Anastatus. These 
sample collections were examined at 
the laboratory and the percentage of 
parasitism in each case was ascertained. 
From the data thus acquired the area 
for general collection of eggs was deter¬ 
mined. The collections made in 1915 
and later do not show the spread from 
the original colony, for in the spring of 
1915 the outside sections of Peabody 
and the surrounding towns were colo¬ 
nized with Anastatus and some of this 
newly colonized area was included 
within the 10 per cent limit. 
The increase year by year in the 
area which included the points showing 
a parasitism of at least 10 per cent, and 
in which most of the egg masses were 
collected, is here presented: 
Acres 
Year occupied 
1910- 11 
1911- 12 
1912- 13 
1913- 14 
1914- 15 
1915- 16 
1916- 17 
1917- 18 
1918- 19 
1919- 20 
1. 7 
2 
12 
234 
242 
903 
2, 261 
3, 915 
8, 008 
8, 198 
