April, ’18] 
WOLCOTT: TRICHOGRAMMA LIGHT RESPONSE 
207 
reactions of the emerging insects, the vials were kept in the dark and 
only exposed to light for a short time each day, when observations on 
emergence were made. 
Upon removing the vials from the dark the great majority would 
show no Trichogramma adults emerged, but as one continued looking 
over them, Trichogramma would begin to appear in vials in which none 
had been visible when first examined. Some of the tiny insects would 
have their wings not yet expanded, and others would show only one 
red eye or the entire head looking out from the hole in the egg'shell, 
but in five or ten minutes the vial would be full of the active little 
wasps. To determine just how definite was this emergence response 
of Trichogramma adults to light, a large number of observations were 
made at various times of day. 
The method of procedure was to remove the vials from a large card¬ 
board mailing tube, with a screw top tin cover, one by one. The 
emerged Trichogramma adults were counted as they left the vial when 
the cork was removed and the open end turned towards the light. 
These vials were placed in order in front of the window, while the 
vials containing egg clusters from which no adults had emerged were 
also placed in regular order in the same situation, but in a separate 
row. At the end of an hour the vials were again examined, Tricho¬ 
gramma adults counted as they left the vials, and the vials returned to 
Material Collected August 1 
Material Collected July 30 
Emerged between 
Emerged between 
Emerged between 
Emerged between 
6 p.m. Aug. 3 and 
9 a. m. and 10 a. m. 
7 p. m. July 30 and 
1.05 p.m. and 
Vial 
9 a.m. Aug. 4 
Aug. 4 
Vial 
1.05 p.m. July 31 
2.05 p.m. July 31 
No. 
No. 
Dark 
Light 
Dark 
Light 
1 
3 
14 
1.10 p.m. 
2 
4 
11 
1 
10 
0 
10 
3 
2 
12 
2 
6 
0 
16 
4 
4 
5 
3 
12 
0 
3 
5 
1 
23 
4 
5 
0 
12 
6 
4 
11 
5 
9 
0 
19 
7 
7 
11 
6 
0 
5 
20 
8 
3 
25 
7 
0 
5 
12 
9 
33 
0 
8 
0 
5 
7 
10 
0 
22 
9 
0 
0 
8 
11 
0 
8 
— 
— 
12 
0 
1 
42 
15 
102+15 
13 
0 
27 
14 
0 
31 
15 
1_A 
0 
1 
42 emerged in Dark 
ID 
1 7 
(J 
A 
27 
15 emerged in 5 minutes Light 
IQ 
u 
A 
4 
117 emerged in 1 hour Light 
19 
u 
0 
17 
7 
Ratio 2.78 
20 
0 
4 
61 
258 
61 emerged in Dark 
253 emerged in 1 hour Light 
Ratio 4.23 
