748 
Journal of Agricultural Research 
Vol. XXI, No. 10 
Table V .—Third dispersion test at Dallas , Tex. Species and sex of marked flies recovered 
in rings of traps about point of liberation 
Trap 
No. 
Dis¬ 
tance 
from 
place 
of re- 
Musca domestica . 
Chrysomya macel ¬ 
laria . 
Ophyra aenes ¬ 
cens . 
Total. 
Grand 
total 
(num¬ 
ber). 
Num¬ 
ber. 
Per cent. 
Num¬ 
ber. 
Per cent. 
Num¬ 
ber. 
Per 
cent. 
Num¬ 
ber. 
Per cent. 
d 
9 
d 
9 
<? 
9 
d 
9 
d 
9 
d 
9 
d 
9 
d 
9 
Miles . 
1 W.... 
4-5 
1 
2 
33-3 
66. 7 
5 
43 
10. 4 
89-6 
0 
0 
0 
0 
6 
45 
11. 8 
88. 2 
51 
1 N. 
4.1 
0 
15 
00. 0 
100. 0 
6 
32 
16. 8 
84.2 
2 
2 
50 
5 ° 
8 
49 
14. 04 
85. 96 
57 
1 E. 
4 - 7 
0 
2 
00. 0 
100. 0 
8 
23 
25.8 
74.2 
0 
0 
0 
0 
8 
25 
24. 2 
75-8 
33 
iS. 
4.6 
1 
9 
10. 0 
90. 0 
4 
34 
10. s 
89- 5 
0 
0 
0 
0 
5 
43 
10. 4 
89-6 
48 
Total... 
2 
28 
6. 67 
93 - 33 
23 
132 
14. 8 
85.2 
2 
2 
50 
50 
27 
162 
14. 29 
85-71 
189 
a W.... 
6.0 
0 
4. 8 
95- 2 
0 
1 
21 
4 - 5 
Q 3 . s 
22 
a N. 
5. 6 
23.08 
76. 92 
17 
15. 0 
85.0 
a E. 
6. 2 
0 
. 0 
100. 0 
0 
13 
. 0 
100. 0 
13 
2 S. 
6.1 
1 
8 
11.1 
88. 9 
3 
10 
23.1 
76.9 
0 
0 
4 
18 
18. 2 
81. 8 
22 
Total... 
4 
19 
17-39 
82.61 
4 
50 
7-4 
92. 6 
0 
0 
8 
69 
IO. 39 
89. 61 
77 
, w.... 
7.0 
0 
0 
6 
. O 
100. 00 
6 
* N. 
6.3 
2 
2 
3 
40. O 
60. 0 
5 
e.:::: 
1 
25. 0 
75 -o 
6 
100.0 
0 
IO. O 
90. 0 
10 
3 s..... 
7-3 
0 
O 
0 
3 
. 0 
100. 0 
0 
0 
0 
3 
. 0 
100. 0 
3 
TotaL.. 
3 
8 
27-3 
72. 7 
0 
13 
. 0 
100. 0 
0 
0 
3 
21 
12. 5 
« 7 - 5 
24 
4 W.... 
" 8.1 
0 
0 
8 
. 0 
100. 0 
0 
0 
0 
IT 
. 0 
100. 0 
11 
4 N..... 
• 7.8 
0 
10. 7 
89. 3 
25 
10. 7 
80. 3 
28 
A E. 
8.0 
0 
7 
. 0 
IOC. 0 
7 
4 3 . 
8.2 
0 
0 
2 
7 
22. 2 
77-8 
0 
0 
2 
7 
22. 2 
77. 8 
9 
Total... 
0 
5 
. 0 
100. 0 
5 
45 
10. 0 
90. 0 
0 
0 
5 
50 
9. T 
90. 9 
55 
Grand 
total.. 
9 
fio 
13.04 
86. 96 
32 
240 
11. 76 
88. 24 
2 
2 
50 
50 
43 
302 
12. 44 
S 7 - 56 
545 
As will be noted, a considerably larger number of marked C hry so my a 
macellaria were recovered, the total being 272. Of these, 155 (57 per 
cent) were taken in the first ring of traps, 54 (19.8 per cent) in the 
second ring, 13 (4.8 per cent) in the third ring, and 50 (18.4 per cent) 
in the fourth ring. It will be noted that a considerable number of 
marked flies of this species were taken in each of the traps in the outer 
ring, which is approximately 8 miles from the point of liberation, the 
maximum distance being 8.2 miles in No. 4 south, where 9 colored flies 
were recovered. The comparatively small number of marked screw- 
worm flies taken in the third ring of traps is noteworthy, but this can be 
explained largely on the basis of the comparatively unfavorable loca¬ 
tion of these traps for the collection of this species. This matter will 
be discussed subsequently. 
The only other species of marked flies captured was Ophyra aenescens, 
four specimens of which were taken in No. 1 north, 4.4 miles from the 
point of liberation. 
