What you need:
empty 2 liter soda bottle
box cutter knife
screwdriver
twine
a bowl
1/2 cup sugar
1/2 cup white vinegar
spoon
How to build the trap:
1. remove the soda bottle cap and throw it away.
2. cut the top of the bottle off, approximately 4 inches from the top (a bit past where the bottle sides straighten out). use the box cutters.
3. Turn the bottle top upside down. push the upper part of the bottle into the lower part of the bottle, so that it forms a sort of funnel.
4. Pierce 4 holes (equi-distant from each other) at the top of the trap (holding the 2 pieces of bottle together.
5. make the tie for the trap as follows:
Thread about 2 feet of twine through each of the 4 holes, put a knot in the twine at each hole. bring the 4 lengths of twine together over the trap and tie them in a knot. This is how you will hang the trap.
6. Mix the trap liquid:
Mix the 1/2 cup sugar and 1/2 cup vinegar until the sugar melts. add the mixture to the trap.
7. Hang the trap where the horse flies are prevelant.
see picture below