68 
BULLETIN 647, TJ. S. DEPARTMENT OE AGRICULTURE. 
full and fumigated the second and third times, and 404 of them the 
fourth time. The next five fumigations were started November 12, 
and December 4, 1914, and January 7, February 25, and June 7, 1915, 
the number of traps fumigated being 409, 403, 405, 305, and 21 at 
each respective fumigation. The number of queens killed in the last 
five fumigations was 34,765, 32,240, 55,080, 19,215, and 4,599, re- 
spectively. 
Before undertaking the work, an agreement had been made be- 
tween the officers of the Bureau of Entomology and the orange grove 
company by which that company was, among other things, to main- 
tain open barrier ditches 1 around the treated block, and keep that 
block of the orchard in a state of clean cultivation at its own expense 
throughout the course of the experiment. Succeeding events, how- 
ever, prevented the company, through no fault of its officers, from 
carrying out its part of the agreement. The result was that the 
ditches were not maintained, and weeds and trash remained in the 
orchard at all times; hence, many ants migrated into the block, 
often being traced directly to the traps, and other nesting places be- 
sides the traps were numerous. The persistent habit of the queen 
ants of forming small offshoot colonies along the worker's trails is 
at once the principal means of spread and a great safeguard to the 
species. In the interval from the second to fifth fumigations, from 
41 to 46 trails of ants were found migrating into the orchards from 
the direction of the levee alone, at every examination. Many ants 
from outside the orchard were, therefore, killed in the traps, and the 
duration of the work was unnecessarily prolonged thereby. The 
record of ants killed at the various fumigations is given in Table 
VIII. 
Table VIII. 
-Results of ant-trapping experiment in an orange grove. 
Louisiana, 191Jf-15. 
Fumiga- 
tion 
No. 
Date of 
beginning. 
Number 
of traps 
necessary 
to fumi- 
gate. 
Estimated 
number of i 
queen ants 
killed. 
Fumiga- 
tion 
No. 
Date of 
beginning. 
Number 
of traps 
necessary 
to fumi- 
gate. 
Estimated 
number of 
queen ants 
killed 
1 
June 23,1914 
Julv 21,1914 
Aug. 26,1914 
334 
7 
Jan. 7, 1915 
Feb. 25,1915 
June 7, 1915 
405 
305 
21 
55,080 
19 215 
2 
415 f buu.uuu 
415 295.895 
8 
3 
9 
4 599 
Sept. 28, 1914 
Nov. 12,1914 
Dec. 4,1914 
404 
409 
403 
265, 428 
34, 765 
32, 240 
Total . 
5 
1 307 222 
6 
1 It should be noted that a ditch of this sort already occurred along each side of the 
orchard from front to back, being constantly necessary to drain off the surface water. 
It was only necessary to clean the weeds out of these ditches and deepen them a little, 
and excavate a short ditch across the front of the place. The ants were prevented from 
coming in at the rear by the marsh. 
