DISPERSION OF ELIES BY FLIGHT 
By F. C. Bishopp, Entomologist, and E. W. Eaake, Entomological Assistant, Inves¬ 
tigations of Insects Affecting the Health of Man and Animals, Bureau of Entomology, 
United States Department of Agriculture 
A definite knowledge of the means of dissemination of various species 
of economic insects is of much importance in control or eradicative 
undertakings. Undoubtedly the spread of injurious forms by artificial 
means is in general of most pronounced importance. With free-flying 
species, however, natural dispersion deserves careful consideration. 
This is particularly true of the various species of flies which directly 
affect man and animals. The accumulation of data on the possibilities of 
flight of various injurious species of flies should aid economic work in 
several ways. 
1. It should help in the study of the spread of fly-borne diseases, 
either in large districts or locally. 
2. It should make possible the proper location of dumps, incinerators, 
hog-feeding stations, and other favorable breeding grounds so that the 
menace to towns, cities, military camps, etc., will be reduced to a 
minimum. 
3. In control work in restricted districts or about individual plants 
it should help in determining the extent to which fly-breeding grounds 
in the neighborhood affect these undertakings. 
4. In the prosecution of large-scale control work against certain 
species on farms or ranges, it should show how widespread must be the 
effort if marked results are to be accomplished. 
5. It should make it possible to determine whether control campaigns 
are accumulative from year to year in their effect, or whether, owing to 
extensive migration, the results are effective only during one year or 
one period. 
Realizing the desirability of collecting data along this line, a number of 
investigators in various parts of the world have carried out dispersion 
tests. These were mainly with the house fly ( Musca domestica h .), although 
limited numbers of a few other species were observed in the experiments. 
Most of these tests were conducted under more or less distinctly urban con¬ 
ditions. The observations and main conclusions of these various experi¬ 
menters have been so well summarized by Parker 1 that they will not be 
repeated here. Parker also discusses rather fully in the same article the 
methods of marking the flies in the tests. 
The maximum range of dispersion recorded up to the work of Parker 
was 1,700 yards. This distance was noted in a test in England carried 
1 Parker, R. R. dispersion or musca domestica linnaeus under city conditions in Montana. 
In Jour. Econ. Ent., vol. 9, no. 3, p. 325-354, pi. 24-26. 1916. 
Journal of Agricultural Research, 
Washington, D. C. 
Vol. XXI, No. 10 
Aug. 15, 1921 
Key No. K-100 
zc 
(729) 
