14 
from this rivalry based upon erroneous instinct, as well as from the 
attacks of hyperparasites. Such mistakes are of course much more 
likely to occur during such times of extraordinary multiplication than 
when the species are normally abundant. 
During the entire series of observations careful records were kept of 
all specimens of Pimpla reared. The following table indicates numbers 
and date- : 
Date 
Num- 
ber. 
5 
15 
12 
6 
9 
12 
22 
55 
96 
90 
76 
25 
20 
7 
4 
5 
I 
4 
3 
12 
7 
5 
8 
Date. 
Num- 
ber. 
6 
5 
:s 
•> 
1 
1 
1 
•j 
1 
2 
6 
11 
9 
18 
8 
9 
19 
14 
Date. 
Num- 
ber. 
Dat( , 
Num- 
ber. 
1895. 
Sept 12 
Oct. 
Nov 
Dec. 
Jan. 
Mar 
1895. 
9 
11 
12 
15 
1896. 
Mar. 19 
20 
21 
23 
24 
26 
27 
30 
31 
Apr. 1 
2 
&'. '.'....'.'.'. 
e 
21 
6 
11 
2 
14 
2 
7 
."> 
1 
3 
2 
3 
1 
1 
I 
4 
8 
1 
5 
19 
1S9G. 
Julv 9 
10 
11 
13 
14 
2 
L3 
23 
14 
Hi 
22 
224 
17 
t; 
9 
14 
19 
G 
50 
18 
1"). .. 
82 
19 
1G. .. 
100 
20 
17 
60 
21 
18 
60 
23 
1896 
!) 
20 
100 
24 
21 
22 
2i.'.'.'.Y.'.V. 
24 
25 
50 
:t 
50 
26 
•>7 
4 
20 
12 
28 
!• 
10 
11 
13 
14 
L6 
10 
<l 
27 
28 
31 
An:. 4 
3 
Oet. l 
•> 
10 
11 
13 
14 
16 
17 
18 
4 
1 
:; 
1 
4 
10 
26 
Total 
2 
1- 
20 
21 
1 
1 , 059 
. 
It will be observed that the periods of greatesl abundance were from 
September 12 to 26, 1895 j from March 9 to 26, 1896; from April 10 to 
20, L896, and from July 10 to 25, 1890. 
The percentage of parasitism by this species was indicated rather 
plainly by four series of experiments. 
From 100 cocoons collected September 
10, 1895, there issued 38 adults; from 
about 500 cocoons collected August 23, 
there issued 300 specimens ; from about 
300 cocoons collected August 21, there 
issued 172; from G04 cocoons collected 
between June 30 and July 8, 189G, 
there issued 729. 
We have not previously stated defi- 
nitely the number of specimens of the 
parasites nourished by a single Orgyia. 
The number in summer varies froml to 
10, with perhaps an average of 3 or 4. 
This number refers to the large well nourished larva', mainly females. In 
the late autumn more are found. Ten to fifteen Pimpla cocoons in a single 
Orgyia cocoon are not at all unusual at this time of the year, while from 
a single Orgyia cocoon collected by Mr. l>usck in September, 1896, were 
reared no less than 23 Pimplas, all of which were males. This i>articu- 
lar Pimpla cocoon mass was cross-sectioned, and is illustrated at fig. 4c. 
..." 
Fig. 4. — "Pimpla inquisitor: a, mass of male 
cocoons: ft, do., cross-sectioned; c, cross 
section of Largest cocoon mass found: <l. 
mass of female cocoons— nat. size (origi- 
nal). 
