88 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
Adult flies of Hylemyia antiqua Meig. and Hylemyia cilicrura Rond, 
were found in the fields in the southern part of New Jersey early in 
March and they continued to be present in small or large numbers during 
April, May and June. This investigation ended June 30, 1923. Most 
of the experiments which are discussed in this report were conducted 
during May and June. Early in May and again after the middle of 
June Hylemyia antiqua Meig., was the most abundant species while 
late in May and early in June adults of Hylemyia cilicrura Rond., 
occurred in large numbers. In the majority of the collections and 
catches of Hylemyia cilicrura Rond, the males outnumbered the females 
but with Hylemyia antiqua Meig., the females equalled or outnumbered 
the males. A more thorough investigation is needed to determine 
definitely the above facts. The past season’s experience convinces the 
author that wherever a chemotropic study is made it is important to 
have complete information on the abundance of the species and the 
normal proportion of the sexes of each species in the territory during 
the entire period of the investigation. 
Methods 
Several methods and apparatuses were used to catch and determine 
the flies which were attracted to odors. After a number of preliminary 
trials a small round wire screen (12 meshes to the linear inch) fly trap 
was adopted as the most satisfactory trap for catching the flies. It 
is probable that a wire screen trap of finer mesh (16 to 20 meshes per 
linear inch) would be more satisfactory. In some instances the smallest 
individuals of Hylemyia cilicrura Rond., were able to work their way 
through the 12 mesh wire-screen. The round trap used was 9 inches 
high, 6 inches wide at the bottom and 4 inches wide at the top. The top 
of the trap was a solid piece of tin with a small handle attached. A 
detachable round wire-screen cone approximately 4 inches high and with 
a small round hole near the top fitted snugly within the bottom of the 
upright portion of the cage. The entire cage including the cone was 
clamped to a tin base and it could be easily detached from the base. 
Under field conditions a long iron spike (six inch nail) was driven through 
the center of the bottom into the ground below and served as an anchor 
for the cage. When properly anchored high winds and beating rains 
did not upset the cages. The bait was placed in a Syracuse watch 
glass on top of the tin base and directly below the hole in the cone. 
In the field the traps were placed between the rows of onions and 25 to 
50 or more feet apart. 
