758 
Journal of Agricultural Research 
Vol. XXI, No. io 
The southwest trap was located on the main highway running north¬ 
west from Dallas. The traffic on this road was of about the same char¬ 
acter and amount as on the road from Dallas north by the point of 
liberation. There was practically no chance of any vehicles going from 
the point of liberation by this trap and no roads giving direct communica¬ 
tion between the two points. 
On October io the first liberation was made. On the preceding day 
the traps were all placed and baited with fresh slime, as in the preceding 
experiments. About 25,000 flies colored with unfading red (paint pig¬ 
ment) were released at 11 a. m. These were secured by means of traps 
set at a packing house on the previous evening. At the time of liberation 
the sun was partly clouded and a slight breeze was blowing from the 
south. Many of the flies went several feet into the air and flew in all 
directions, while others settled on the hedge and vegetation near by. At 
4.30 p. m. the same afternoon about 20,000 flies taken in traps at the 
packing house since the morning were colored in the same way and 
released. At that hour it was cloudy and cool. The flies did not show 
a tendency to remain on the cages and on the persons of the writers as 
in the previous experiment. Most of them settled on the hedge and 
other vegetation near. 
On October 11, at 11 a. m., a third liberation of about 15,000 flies was 
made. These flies were secured the previous afternoon at the packing 
house. At 4 * 3 ° P* aa additional lot of about 20,000 flies colored in 
the same way was liberated. The clouds were heavy and a light shower 
fell just prior to liberation. 
A sample of the flies liberated on the first day was examined to deter¬ 
mine the proportion of the species and sex. The results were as follows: 
Musca domestica 66.4 per cent, Chrysomya macellaria 28.5 per cent, 
Phormia regina 3 per cent, Lucilia sericata 1 per cent, Ophyra spp. 0.7 
per cent, Hydrotaea dentipes Fab. 0.4 per cent. The estimated percent¬ 
age of species in the lots liberated on the succeeding day agreed closely 
with these figures. 
The approximate averages of these species in the total catch in the 16 
recovery traps were: Musca domestica 68 per cent, Chrysomya macellaria 
1 3 per cent, Phormia regina 10 per cent, Ophyra spp. 1 per cent, and other 
species 8 per cent. 
Of the 39 marked flies recovered 33.3 per cent were Musca domestica , 
23.1 per cent Chrysomya macellaria , 41 per cent Phormia regina , 2.6 per 
cent Ophyra leucostoma. The large percentage of P. regina recovered, 
as compared with the other species, is striking. This may no doubt be 
explained in part at least by the fact that the cooler temperatures of fall 
were more favorable for the diffusion and recoveiy of that species than 
of the house fly and screw-worm fly. In this experiment, as in the last, 
the percentage of marked house flies recovered is about one-half of the 
