February, '17] ENTOMOLOGISTS' DISCUSSIONS 169 



wheat in fall or spring, they fly very closely to the plants, flying short 

 distances along the wheat row, touching the ground and plants fre- 

 quently. I have seen them so thick in the fields at times that one 

 would imagine that they were gnats and it only required that one be 

 caught for examination to determine that they were not gnats. Dur- 

 ing the spring of 1913, 1 believe it was, I decided that I wanted to deter- 

 mine how high the adult flies would fly. I built a large frame, covering 

 it with boards, and set it north and south, or rather, facing the south, 

 because the wind was blowing from that direction. Tanglefoot papers, 

 such as are used to catch flies in the dining rooms, were tacked to the 

 board ; I was amazed to find that I got flies no higher than about seven 

 inches from the ground. I followed that observation again the next 

 fall with the same apparatus, making similar observations. In the 

 fall of 1914 I built a frame and covered it with wire screen. The 

 screens were built in an infested wheat stubble field 3 feet high and 9 

 feet long, placed at right angles — one to catch flies which went east 

 and west, and one to catch those that went north and south. They 

 were painted with very thin tanglefoot in order to catch them and hold 

 them fast. The flies being numerous at this time, less than five minutes 

 were required to catch a number. I then noticed they were flying over 

 the three-foot screen. I immediately proceeded to build one twelve 

 feet high, placing it near the low one. By use of a step-ladder I found 

 they were flying over the 12-foot board frame. The 12-foot screen 

 caught large numbers; the amounts I will not attempt to give you. 

 The peculiar thing which bears out Mr. McColloch's discussion regard- 

 ing the wind was that the flies were alwaj^s flying in the direction of the 

 wind. One interesting observation was made in connection with the 

 screen placed at the west edge of the field. The wind was blowing 

 toward the west, from the direction of the infested field, many adults 

 being caught. In thirty minutes or less, after the screen was erected, 

 the wind changed, coming directly from the west and those flies which 

 had been blown into a cornfield on the other side, or west, came back, 

 or were blown back. This gave us indications, however, that the flies 

 were flying higher than 12 feet and we accordingly erected a screen 

 about 14 feet wide and ran it up 30 feet. We got flies at the top of 

 the screen. 



In 1915, I continued the observations on a screen 14 feet wide and 

 30 feet tall, erected near wheat fields. The flies were flying 30 feet 

 regularly, but the majority were between 19 and 21 feet, and most of 

 them on the 21st space. 



Mr. T. J. Headlee: I should like to inquire whether the speaker 

 or any one else here has any data to show the character of the wind that 

 produced this flight. 



