CHEMOTEOPIC TESTS WITH THE SCEEW-WOEM FLY 7 
entering the treated and check jars each day, as expressed in the 
daily ratios. 
It was observed in the course of the experiments that when the 
baits in the check jars became very heavily infested by larvae, as 
was often the case, their attractiveness diminished toward the end 
of the period of exposure and was sometimes completely lost. This 
tended to place the jars which were treated with a more or less 
effective repellent, and hence not infested, at a disadvantage when 
compared with the unattractive check during the last day or two 
of the test. 
In addition to observations of the number of each species of fly 
present in the jar at two-hour intervals, observations were made as 
to the presence of eggs or larvae. The degree of infestation was 
observed to vary greatly, as indicated by the number of egg masses 
deposited and the number of larvae which were present in the different 
jars at the close of each test. As no effort was made to determine 
the actual number of eggs deposited, the results are reported as 
number of infested treated jars over number of infested check jars. 
Furthermore, since it is impossible by a cursory examination to de- 
termine the species of egg or larva, these infestation figures apply 
to all species, except perhaps the house fly, which infests fresh meat 
so little that it can be neglected. The species responsible for the 
infestation was determined by transferring the eggs or larvae in the 
jars at the end of the five-day test period to fresh meat and allowing 
the adults to emerge in screened cages. The emergence data are 
shown by giving the number of treated jars from which they emerged, 
no account being taken of the number of flies bred out. The emer- 
gence data are incomplete, owing to the difficulties inherent in hand- 
ling so much material and to the escape of larvae from the cages. 
The fact is recognized that the tests of many of the materials are 
insufficient both as regards the number of flies present when the tests 
were conducted and the variety of conditions, such as climatic con- 
ditions or dilution of materials, under which a given material was 
exposed. These matters have been given some consideration in the 
"Discussion of results/' p. 22. 
TABULAR STATEMENT OF RESULTS OF TESTS 
The results of the chemotropic tests with screw-worm flies are 
presented in Table 1 . 
