Aug. 15, 1921 
Dispersion of Flies by Flight 
745 
number captured after this date. The house flies appear to have become 
widely disseminated by the end of the second day, and the maximum 
number was recovered on the fourth day (July 15). This maximum, 
however, was not attained through large numbers being captured in the 
more distant traps but by an increased catch in the two inner rings. 
The trapping was continued until July 26, the last C. maccllaria being 
captured on the eleventh day (July 22), one specimen appearing on that 
date in each of traps No. 4 north and No. 4 south. The last house flies 
recovered were taken on the same date, one each in No. 1 south and 
No. 3 south. In No. 2 north 7 house flies were recovered on July 21, 
a much larger proportion on this late date than was observed in any 
other trap. The total in this trap was 29. 
Several Phormia regina out of a total of 26 recovered were taken soon 
after liberation, one appearing in No. 2 west and three in No. 3 west on 
the first day. The last P. regina was recovered on the tenth day 
(July 21) in No. 3 west. 
There were too few specimens of Ophyra liberated or recovered to 
draw conclusions, but it may be stated that the first specimens recovered 
were taken in No. 3 west, No. 2 north, and No. 1 south (one in each) on 
the third day after liberation and the last in No. 2 west on the seventh 
day (July 18). 
THIRD DISPERSION TEST AT DALTAS, TEX. 
The evidence secured in the second test very clearly indicated that the 
maximum distance of normal dispersion of the various species of flies 
was far greater than the outer circle of traps in that test, which was 
approximately 5 miles. Accordingly plans were laid for another test to 
determine if possible the maximum distance of dissemination. For this 
test the region lying to the north of Dallas was chosen. The point of 
liberation selected was approximately 7 miles from the edge of the city 
of Dallas on the main north and south thoroughfare known as “ Kings 
Highway.” This region is highly developed agriculturally, being thickly 
dotted in all directions with farms, most of which maintain some live 
stock. The contour of the country is not markedly different from that 
where the first and second tests east of Dallas were conducted. Within 
the area under consideration are a number of creeks bordered with woods 
of greater or less width. For the most part, however, the country is 
open cultivated land more or less closely covered with a network of roads, 
several steam railways, and one electric line. As has been stated, the 
point of liberation was on the most heavily traveled highway running 
north from Dallas. On this road, about 4 miles south of the point of 
liberation, is the town of Vickery (about 100 population) and to the north 
1 mile the town of Richardson (500 population), Plano (1,700 population) 
6 >2 miles, and Allen (300 population) 13 miles. To the east are a number 
