After I established a feedlot on my farm, hordes of flies arrived and irritated the cattle, prompting this idea for a cheap fly trap, using empty 2-litre plastic soda bottles. First, cut off the top of a bottle to create a funnel (discard the cap). Push the upside-down funnel down to near the bottom of the cut bottle, where it will be held in position. Next, repeat the exercise with a similar-sized bottle, this time retaining the cap.
Glue the capped funnel to the open end of the first cut bottle. Now you have a complete soda bottle with a funnel inside (see picture). Invert the bottle and, using a sharp knife, cut 1 cm-diameter holes on the sides of the five knobby “feet”; this will allow flies to enter the trap. Thread a piece of string or wire through two of the holes to create a means to hang your fly trap.
Remove the lid and hold the bottle nearly upright while you insert a suitable bait (basically, anything rotten that will attract flies). The flies will enter through the holes on the side and make their way down towards the bait through the funnel. After gorging themselves, they will try to fly away, but instead will become trapped. When your trap is filled with dead flies, you can open the lid, dispose of the little corpses and start over. Caution: hang the fly trap in your garden and not inside the house.
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