The Cone Fly Trap: Up to the Light, Down Into the Water

"This invention consists in the combination of a vessel in the shape of a truncated cone, open at the top, and having guides at its lower end, in which is placed a sliding bottom, above which are notches at the base of the cone, in combination with another vessel, also in the shape of a truncated cone, but inverted and secured at its lower end to the outside of the one first mentioned in such manner as to form a channel annular and V-shaped, in cross-section, between the two cones, the upper of which is provided with a glass cover, all for the purpose of trapping flies in the manner hereinafter set forth." Fly-bait "allures the insects, which pass through the notches". "Having eaten their fill they naturally fly upward toward the light shining through the aperture". "On striking the glass cover they are thereby dashed downward and fall into the channel", "which should contain water".

Cut the top third off a clear plastic bottle, turn it upside down and push it into the bottom part as a funnel, and tape the join. Pour in a little bait: sugar dissolved in water with a splash of vinegar. Set it in a sunny place where flies gather, next to an open saucer of the same bait for comparison. Count the flies in the trap, and on the saucer, at the same time each day for a week. Note how many leave the saucer and how few leave the trap.

**Louis Grim** of Fort Branch, Gibson County, Indiana, received US 118,852, dated 12 September 1871; half the right was assigned to Alexander I. Moore of the same place. **Honest limits.** The model treats each escape attempt as independent and the floor as uniformly likely; real flies follow walls and light more cleverly and less. Sizes and bias are examples. Your daily counts are the measurement.