- 
PARASITES OF GIPSY-MOTH PUP. 247 
tory as could be expected. The collections of nests from areas II and 
III on the map (Pl. XXIJ) produced the parasite in abundance, and in 
area I, throughout which it was found the winter before, it was very 
much more abundant, as will be seen by reference to the tabulated 
summary of the results of the work for the winter in Table X. 
TABLE X.— Monodontomerus xreus as distributed over its area of dispersion.' 
E | 
= Number | Monodon- - Number |Monodon- 
eed of Mono-| tomerus he cae, of Mono- | tomerus 
Section.| Year. ° il | donto- | per 1,000 | Section. Year. | tail nests| Gonte- | per 1,000 
See Lag merus brown- || ‘ tad merus brown- 
Collected. recovered. tail nests. | ea * recovered.) tail nests. 
| 1908 5,574 39 6 4 1910 1, 698 234 | 137 
1 1909 2, 200 708 376 5 | 1910 701 215 | 305 
1910 1,508 495 328 | 6 1910 2, 836 521 183 
1908 947 0 || 7 1910 1,050 260 246 
2 1909 1,107 124 112 || 8 1910 555 86 | 151 
1910 700 182 260 9 1910 825 538 | 652 
3 1909 770 34 49 || 10 1910 500 A} 2 
{ 1910 260 13 50 || 11 1910 1, 600 95 59 
1 Refer to the map (Pl. X XII) for the area included in each section. 
TABLE REPRESENTING THE RAPID MULTIPLICATION OF MONODONTOMERUS IN THE FIELD. 
| Monodon- 
Brown-tail| Monodon- tomerus 
nests col- tomerus per 1,000 
lected. recovered. brown-tail 
nests. 
WEEE Ue be ae ee 1 ee 1,927 | , 168 | 87 
PRCLAPC OF SeChons > ANG 32M 1910 | 22 os ooo bce ee EL 960 190 199 
In 1910 a fairly satisfactory number of the parasites was reared 
from collections of brown-tail moth cocoons made in the field, but 
when the gipsy-moth pupz were examined in the field as in 1909, 
scarcely if any more were found to be parasitized. This was any- 
thing but encouraging, because it had been expected that parasitism 
would amount to at least 1 per cent, if the rate of increase which had 
prevailed up to 1909 had continued. It appeared that the Monodon- 
tomerus was either inclined to pass over the gipsy-moth pup in 
favor of other hosts, or else that its rate of increase had received a 
sudden check before it was sufliciently abundant to become of aid in 
the control of the moth. As before, that winter’s work was anticipated 
with interest since its results would be more directly comparable with 
those of the year before than was that summer’s work. 
The collections of winter webs were first made in the territory 
included within the range of the parasite in the winter of 1909-10 
(areas I, II, and III), and the fact soon became manifest that instead 
of increasing it had actually decreased in abundance throughout that 
territory in the course of the year. It was inexplicable, in view of the 
unlimited opportunities for increase, and it was, to say the least, 
discouraging. 
