68 



BULLETIN 647, U. S. DEPARTMENT OP 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, 1914-15. 



Fumiga- 

 tion 



No. 



Date of 



beginning. 



SSf« 1 Estimated 

 °"™PiL ' number of 

 necessary ,,„„„„ ant . s 

 tofumi- q ^u e f tS 

 gate. KUlm - 



Fumiga- 

 tion 

 No. 



Date of 



beginning. 



Number 

 oftraps 

 necessary 

 to fumi- 

 gate. 



Estimated 



number of 



queen ants 



killed 



1 



June 23,1914 

 Julv 21,1914 

 Aug. 26,1914 

 Sept. 28, 1914 

 Nov. 12, 1914 

 Dec. 4, 1914 



HI } 600,000 



415 i 295,895 

 404 265,428 

 409 34,765 

 403 32, 240 



7 



Jan. 7,1915 

 Feb. 25,1915 

 June 7, 1915 



405 



305 



21 



55,080 



2 



8 



19 215 



3 



9 



4' 599 





Total 





5 



1,307 222 



6 















J It she 

 orchard i 

 It was oi 

 and esca 1 

 coming ii 



uld be noted 

 rom front to 

 lly necessary 

 ?ate a short < 

 > at the rear 



that a ditch of this 

 back, being constant 

 to clean the weeds ov 

 iitch across the front 

 by the marsh. 



*ort alread 

 y necessar 

 t of these 

 of the plac 



y occurred al 

 y to drain o 

 ditches and 

 e. The ants 



ong each 

 Ef the sur 

 deepen th 

 were prei 



side of the 

 face water, 

 em a little, 

 r ented from 



