570 
Journal of Agricultural Research 
Vol. XXXI, No. 
cially adapted standardized rain gauges and are shown in inches plus 
or minus from the normal, the amount for each preceding 24 hours 
being recorded at 5 p. m. Readings for each factor were made, and 
the accumulated variations are given in Table I. 
f 
Table I .—Accumulated variation 19-day period, April 12 to SO, 1917 
Factor 
Cage A 
Cage B 
Cage C 
Cage D 
Cage E 
Cage F 
Time 
Minimum temperature (°F.)___ 
Temperature (° F.). 
Evaporation (c. c.)_ 
Rainfall (inches). 
+34.5 
( +9.5 
< -21.5 
l -8.0 
-80.4 
-.49 
+32.0 
-5.0 
-33.0 
-15.0 
-110.4 
-.16 
+22.5 
-26.0 
-103.0 
-51.0 
-223.2 
-1.57 
+51.5 
-25.0 
-141.5 
-65.0 
-282.1 
-3.24 
+26.0 , 
-2.0 
-39.5 
-26.0 
-118.8 
-.53 
+31.5 
-2.5 
-17.5 
-24.0 
-104.9 
-.59 
8 a. m. 
12 m. 
4 p. m. 
8 a. m. 
5 p. m. 
SECOND TRIAL, LA FAYETTE, IND., MARCH 15 TO 24, 1920 
In order to make an extra tri^tl, it was decided to run the cages 
indoors, thus forcing the adult flies to emerge by artificial heat. 
The cages were arranged in the laboratory under conditions as nearly 
uniform as possible. 
The disadvantage pointed out in the first trial, namely, the 
existence of an uncertainty as to whether about the same number 
of flies emerged in each cage, was recognized, and an attempt made to 
eliminate it. Twelve thousand “flaxseeds” (fig. 2, C) were taken from 
wheat plants killed by the regular fall brood of the fly, and after being 
thoroughly mixed so that thp entire lot would be uniform, they were 
divided into smaller lots,|$nd 1,5QQ. each were placed over moist 
soil in small rectangular fin boxes, and then exposed, one box in 
each cage. An additional 1,500 flaxseeds were placed in till parasite 
boxes, and the adult flies allowed to emerge into glass vials. By 
counting these daily, and also those in the boxes, a suitable control 
was obtained on the total number which could reasonably be expected 
to emerge from each 1,500 flaxseeds in each of the cages. 
Flies were counted and removed from the cages daily, as in the 
preceding trial, except that the record of males and females was 
kept separate, as follows: 
Cage A, 205 females, 539 males, total 744; B, 127 females, 453 
males, total 580; C, 21 females, 32 males, total 53; D, 307 females, 
355 males, total 662; E, 195 females, 527 males, total 722; F, 136 
females, 435 males, total 571; control, 512 females, 601 males, total 
1,113. 
No attempt is made to consider this trial as being conducted under 
any other than extremely unnatural conditions; however, it does give 
considerable information on the subject. It brings out the fact that 
although moisture and temperature may be the controlling factors in the 
emergence of adult flies, wind is certainly of some importance in the 
determination of cage efficiency. Indeed, the percentage of recovery 
is very remarkable in most cases, the exception being cage C, which 
will undoubtedly prove to be too inefficient to merit further con¬ 
sideration. Another remarkable point brought out in this experi¬ 
ment is the fact that from 1,500 flaxseeds used in the control, 1,113 
adult flies were obtained, thus indicating that the very high rate of 
74 per cent of the flies survived the winter, parasitism, and other 
