Oct. io, 1913 
Serpentine Leaf-Miner 
77 
3 contained healthy larvae and 2 healthy pupae of Agromyza, while the 
remaining 42 mines, or 89.7 per cent of those examined, contained para¬ 
sites. Of these 42 mines, 25 contained parasitized larvae, 14 parasitized 
pupae, and 3 were doubtful. Of the 25 parasitized larvae, 20 carried 1, 
and 5 carried 2 external parasites, making 30 parasites on the 25 larvae 
of the leaf-miner; these, with the 14 parasitized pupae, make a total of 
44 individual parasites within the 45 mined leaves. In the Salt Lake 
Basin from June to October, 1911, 75 to 90 per cent of the mines in 
alfalfa leaves were found to be parasitized. 
At Sacaton, Ariz., as early as May 25, 1912, Mr. R. N. Wilson, of the 
Bureau of Entomology, found 89 per cent of the insects issuing from 
mines of Agromyza pusilla to be parasites, while from material collected 
there in June and July parasites alone emerged. 
Mr. Wildermuth, at Tempe, Ariz., from experiments conducted during 
the season of 1912, found that much the same degrees of parasitism 
existed in that locality; and while no record was kept to show the number 
of parasites found in occupied mines, Table II shows the number of adults 
and parasites which issued from large numbers of leaves containing Agro¬ 
myza larvae, collected in the field and kept in jars in the laboratory. 
Table II .—Emergence of Agromyza pusilla and its larval parasites in Arizona and 
California in IQI2 . 
Date leaves 
were 
collected. 
Locality. 
Experiment 
No. 
Number of 
Agromyza 
issued. 
Number of 
parasites 
issued. 
Percentage 
of parasites to 
total insects 
issuing. 
May 
8 
Tempe, Ariz. 
1 
2 
80 
97 
May 
10 
.do... 
4 
4 
33 
89 
May 
14 
.do ... 
6 
5 
4 i 
89 
May 
23 
.do . ... 
8 
0 
68 
IOO 
May 
3 1 
.do. 
9 
3 
3 i 
91 
June 
10 
.do. 
10 
0 
40 
IOO 
Sept. 
20 
.do. 
J 3 
2 
12 
86 
Oct. 
1 
.do .... 
14 
3 
22 
88 
Do 
. do... 
1 3 
c 
24 
83 
Oct. 
14 
.do... 
J 
l6 
D 
3 
12 
0 
80 
Oct. 
18 
.do.. 
17 
8 
19 
70 
Oct. 
19 
.do. 
18 
1 
12 
92 
Do . 
. . .do. 
10 
1 
20 
QEJ 
Do 
.. do. 
y 
20 
0 
16 
7J 
64 
Nov. 
2 
.do. 
21 
30 
48 
6l 
Apr. 
18 
Total. 
HI Centro, Cal. 
76 
6 
478 
18 . 
86. 2 
Apr. 
20 
Brawley, Cal. 
4 
12 
/ J 
7c 
Apr. 
22 
Bard, Cal. 
1 
8 
88 
As will be noted in Table II, the high percentage of parasitism falls 
off rapidly upon the approach of cool weather, thus enabling the insect 
to enter hibernation with a much reduced degree of parasitism. At 
Lakeland, Ela., where no hibernation occurs, Mr. G. G. Ainslie records 
