Journal of Agricultural Research 
Vol. XXI, No. 10 
762 
The proportion of sexes among the released flies as indicated by 
examination of a sample at the time of release was: Musca domestica , 
34 per cent males, 66 per cent females; Chrysomya macellaria, 6 per cent 
males, 94 per cent females; Phormia regina, 22 per cent males, 78 per 
cent females; Ophyra leucostoma, 100 per cent males; Lucilia sericata t 
100 per cent females. In the case of the house fly we would have 
expected to recover a few males if that sex had shown migratory tenden¬ 
cies equal to the female, but with C. macellaria the percentage of males 
released was so small and the number of marked flies recovered so few 
that we would hardly expect to recapture any males. 
RELATION BETWEEN POSITION OE TRAP AND NUMBER AND SPECIES OF 
FLIES CAPTURED 
, As in the previous test, the number and percentage of different species 
,pf flies captured in the different traps varied considerably. During the 
period covered by the test , a total of 12,811 gm. of flies were taken. 
Jn this test the average catch per trap of all species was: West, 762 gm.; 
nprth, 1,212, gm.; east, 587. gm.; south, 1,229 gm.; : southeast, 454 gm,; 
southwest,, 732 gm. The size of , the total catches in different traps in 
either direction varied greatly, especially in the five traps to the west. 
It, appears quite, certain that traps set in situations favorable for flies 
.#nd where, a comparatively large catch is obtained would be more likely 
to capture marked individuals coming to that locality. Furthermore, 
those Traps which are situated most favorably for catching house flies 
would, other conditions being equal, show a larger percentage of marked 
house flies as compared with marked blowflies, and the reverse is equally 
true. : This factor probably had some influence on the results in the 
present test, although the comparatively small number of marked flies 
captured makes the drawing of conclusions on this point unwarranted. 
LONGEVITY OF MARKED ELIES 
In addition to the fact that we are concerned with the possible adverse 
effects of handling and marking the flies used in these various tests, 
there is presented an opportunity of determining the facts as to the 
longevity of several species of flies under natural or unrestrained 
conditions. 
It is apparent also that longevity must play an important part in the 
securing of records on dissemination by the method used in these tests. 
Since few flies were colored in proportion to the area covered by the 
recovery traps, especially in the last two tests, and since under such 
conditions we can hope to capture but a small portion of the flies in the 
area or even in the vicinity of the traps, each additional day of life and 
activity of the marked flies enhances the chances of capturing them. 
In the several tests the following records of longevity were obtained: 
First test at Dallas (radius of dispersion 3 miles), Musca domestica 11 to 
