Aug. X5, x9ax 
Dispersion of Flies by Flight 765 
I3* I 4 niiles; Chrysomya macellaria, 15.1 miles; Phormia regina, 10.9 miles; 
Lucilia sericata, 1.2 miles; L,. Caesar, 3.5 miles; Synthesiomyia brasiliana, 
0.5 mile; Sarcophaga spp., 3 miles; Ophyra leucostoma, 7 miles; O. 
aenescens, 4.1 miles. 
The estimated total number of marked flies liberated in all the experi¬ 
ments reported upon was 234,000. 
In these tests it is considered that too few individuals of species other 
than Musca domestica , Chrysomya macellaria , and Phormia regina were 
liberated to form a reliable guide to their dissemination tendencies. 
Marked flies of all species dispersed in all directions from the point of 
liberation. 
Among the stimuli inducing dispersion the desire for food and the 
desire for places for opposition appear to be among the strongest. 
The fact that many towns, farmhouses, and other favorable feeding 
and breeding grounds were passed by the flies shows that Musca domes- 
tica, Chrysomya macellaria , and Phormia regina at least are not satisfied 
by the mere finding of these places but have marked migratory habits. 
Chrysomya macellaria evinces stronger tendencies toward migration 
than does Musca domestica. This tendency in Phormia regina under opti¬ 
mum climatic conditions for the species is probably equal to that in C. 
macellaria. The other species were liberated in numbers too few for con¬ 
clusions to be drawn, but Ophyra leucostoma and 0 . aenescens show 
marked ability to travel considerable distances. 
The exact relation between direction of dispersion and direction of 
wind could not be determined from the results of these experiments 
because of the choppy wind conditions experienced. There appears to 
be a tendency for Musca domestica and Chrysomya macellaria to go with 
the wind in greatest numbers, but they are shown to travel against and 
at right angles with it as well. It is concluded that under natural con¬ 
ditions the influence of moderate winds on dissemination is not of great 
importance. 
The evidence gained justifies the conclusion that the passing of vehicles 
along the highways was not a dominating factor in the dispersion of 
any species of flies in these tests. This does not mean, however, that 
flies under other conditions may not be widely scattered by artificial 
means. 
These tests show that the house fly, screw-worm fly, and black blow¬ 
fly spread rapidly for many miles. Chrysomya macellaria was recorded 
about 8 miles from the point of liberation in less than 24 hours and 10 
miles m less than 48 hours after liberation. Phormia regina was recovered 
about 11 miles away in less than 48 hours after release. Musca domes¬ 
tica was recovered over 6 miles from the point of release in less than 24 
hours. ^ 
Males as well as females of the principal species used in these experi¬ 
ments may travel many miles. 
