April, * 18 ] 
WOLCOTT: TRICHOGRAMMA LIGHT RESPONSE 
205 
but that work can go on with much more hope and encouragement if 
the “bogy” of the diseased bee-tree and the wide transmission of this 
disease by infected honey can be first eliminated from the minds of 
the people in country districts and in their place substituted a hope 
and expectation of freedom from the disease as a result of the “area 
clean-up” method of treatment. 
[Papers read by Title] 
AN EMERGENCE RESPONSE OF TRICHOGRAMMA MINUTUM 
RILEY TO LIGHT 1 
By George N. Wolcott 
While temporarily employed by the U. S. Bureau of Entomology 
from June to August, 1917, to work on sugar-cane insects in the Rio 
Grande Valley, Texas, the writer collected large numbers of egg clus¬ 
ters of the sugar-cane moth stalk borer, Diatrcea saccharalis Fabr. After 
trying various localities in the valley where sugar-cane was grown, 
Harlingen, Texas, was selected for continuous work, as in two fields 
there about a mile north of the railroad station, Diatrcea was very 
abundant. In all, 1,506 clusters were collected from these two fields, 
and of these 944, or 62.6 per cent, were parasitized by the hymenop- 
teron, Trichogramma minutum. 
The individual Diatrcea egg is oval and flattened, lenticular in cross- 
section, and these plate-like eggs are deposited in single, double or 
triple (or irregularly four, five, and sometimes even six) rows, over¬ 
lapping like shingles or slates on a roof. The following table gives the 
number of eggs in the masses, and the frequency with which different 
numbers occurred: 
Number 
Frequency 
Number 
Frequency 
Number 
Frequency 
3 
2 
18 
66 
33 
19 
4 
1 
19 
76 
34 
14 
5 
1 
20 
50 
35 
16 
6 
7 
21 
56 
36 
11 
7 
19 
22 
55 
37 
10 
8 
20 
23 
53 
38 
11 
9 
35 
24 
44 
39 
5 
10 
38 
25 
40 
40 
5 
11 
47 
26 
30 
41 
11 
12 
48 
27 
36 
42 
4 
13 
50 
28 
27 ■ 
43 
6 
14 
49 
29 
17 
44 
2 
15 
64 
30 
21 
45 
6 
16 
63 
31 
11 
46 
5 
> 17 66 32 27 47 
1 Published by permission of the Chief of the Bureau of Entomology. 
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