A NEW TECHNIQUE IN CONTROL OF THE HOUSE FLY 
Willis N. Bruce, Associate Entomologist, Natural History Survey Division 
Since about 1950, an increasing degree of tolerance to residual sprays 
has been noted in populations of the house fly, Musca domestica Linnaeus, in 
most parts of the United States. 
A public that placed too much dependence on residual insecticides and 
too little on sanitation as a means of house fly control has been forced to turn 
from residuals to chemicals of only temporary effectiveness. 
In the past three years, space sprays containing pyrethrins and baits 
containing TEPP (tetraethylpyrophosphate) have gained some popularity. None 
has given lasting relief except when applied at intervals of a few hours or a few 
days. TEPP possesses the disadvantage of considerable hazard to the health 
of animals it is designed to protect and of even greater hazard to persons 
applying it. 
MATERIALS AND ME'THODS 
In April, 1953, the author began a series of laboratory tests with a di- 
alkylphosphate known as Bayer L 13/59. A bait consisting of 1$ grams of 
Bayer L 13/59, 1 pound of granular sugar, and 3 gallons of water gave a high 
degree of control of house fly populations for 2 or 3 days. 
The effective period of the bait, which was made in accordance with 
directions furnished by the manufacturer of Bayer L 13/59, was little better 
than that for TEPP and therefore held small possibility of greater usefulness 
to farmers and other potential users of fly baits. 
In mid-June, 1953, the author began another series of tests, tables 1 and 
2, with a bait consisting of 15 grams of Bayer L 13/59, dissolved in about 
4 ounces of water, and thoroughly mixed into 1 pint of dark Karo syrup. 
This bait was applied in small quantities with a paint brush, fig. 1, to 
relatively smooth surfaces where flies tended to congregate. Results of 
laboratory tests are given in table 1 and of field tests in table 2. 
In barns, the bait was applied to posts, fig. 1, window frames, fig. 2, 
and partitions, fig. 3, and to strings or wires hanging from ceilings. In and 
around other premises, it was applied to window frames, edges of window 
Screens and screen doors, on the outsides of garbage cans, and on pieces of 
paper or cardboard placed where flies were seen to alight. Only a small 
amount of the bait was applied in any one building, table 2. 
ays 
