332 journal of economic entomology [vol. 9 



Establishment of Recapture Stations and Placing of Traps 

 The most satisfactory results would have been obtained if it had been 

 possible to select a large number of stations and collect the trapa at 

 one- or two-day intervals during the whole season. Due to the re- 

 quirements of other work which was carried on at the same time 

 and insufficient assistance for a plan such as the above, the following 

 scheme was adopted. Traps were placed in three series, those of 

 each series at first centering about the Laboratory, Sales Yards and 

 City Dump release points, the series being known respectively by 

 these names. It was planned to place ten traps in each series and to 

 collect them twice a week at alternating three- and four-day intervals. 

 In the main this was followed, but variation from the schedule was 

 sometimes necessaiy. Each series of traps was left at a given set of 

 stations for only a few settings and then new stations were selected 

 at constantly increasing distances. In this way it was possible to 

 cover the whole city though some parts much more thoroughly than 

 others. Stations of the Laboratory series were numbered from 1, 

 those of the Sales Yards series from 101, those of the City Dump 

 series from 201. Stores from which records were taken from sticky fly 

 paper were assigned a station number corresponding to the locality. 



With few exceptions the records are from Hodge traps placed out- 

 of-doors. For the purposes of this work, which was to find in what 

 localities the flies could be recaptured, the out-door results were all 

 that were necessary and the use of traps instead of sticky fly paper 

 permitted a larger number of flies to be captured. All in-door records 

 are designated by reference to a foot-note. Beer and oatmeal were used 

 as a bait for the traps.* 



Method of Collecting Traps 

 When collecting traps the tops were removed and the hole for 

 entrance plugged with cotton. The pans were rebaited and new 

 tops put in place. 



Method of Marking Flies 



Stains Used. — Flies released from the several release points were 

 stained as follows: Laboratory, acid fuchsin; Sales Yards, rosolic acid; 

 City Dump, aqueous eosin; Washington School, trypanblau. Those 

 released from the Sales Yards on August 5, 6 and 7, were stained with 

 methylene green; this was done with the hope that by subsequent re- 

 captures some idea could be obtained of the average life of the house- 

 fly. The results were unsatisfactory, however. 



Preparation or Stains.— Stains were prepared as follows: Acid 

 fuchsin, 4 c.c, 10 per cent alcohol, 100 c.c; rosolic acid, 4 c.c. dissolved 



* In the work during 1914 it was found that beer and oatmeal were two to three 

 times as efficient as beer alone and afforded a standard bait. 



