A Simple Fly Trap

Backgrounder

Nearly every farmer in the world has trouble with stable flies (Stomoxys spp.) – those pesky blood-sucking flies that carry disease to cows and other livestock.  Here’s an easy way to get rid of them.  It comes from farmers on the island of Mauritius in the Indian Ocean.

To start off, they keep their cows in dark sheds because they know that the flies like to be where it is light.  But some flies always get in and bother the cows anyway.

So here is what the farmers do.  They build a trap to catch as many flies as possible.  Then they either kill the flies or put them outside the cow shed.

Here is how to build the trap.  Get 12 pieces of wood.  Each stick of wood should be 1 centimetre square and 45 centimetres long.  Make a wooden frame the shape of a box with these sticks of wood.  You could also use heavy wire to make the frame.  Cover each side of the box with fine nylon netting.  Now you have a box with sides made of nylon netting.  Cut a small hole – about 2 centimetres wide – in the netting at the centre of one side of the box.

Where should you put the trap?  You must cut a hole — exactly the same size as the box — in one wall of your cow shed.  The  hole should be at least one metre above the floor.  Then push the nylon box into the hole in the wall of the shed.  Push it only halfway, so that half of the box is inside the shed and half of the box is outside.  Make sure the side with the hole is on the inside of the barn.

Now let’s think about how to get the flies into the box.

As you know, stable flies always try to fly toward the light.  The flies in the barn will see the light coming through the box and will fly over to it.  They will want to fly right through the box to the outside where there is even more light.  The flies will walk or fly around the netting trying to find a way through.  Eventually they will find the hole and fly through.  Then they will fly toward the outer wall of nylon netting.  But they cannot fly through it.  The flies do not want to fly back toward the darkness of the cow shed so it is unlikely that they will find their way out of the trap through the small hole that you made.  You have trapped them.

You can make it even easier for flies to get into your trap.  By slightly changing the wooden frame for the nylon box, you can make the area around the entrance hole funnel-shaped, so that it is easier for the flies to get in but much harder for them to get out.

Flies have an odor and buzzing sound that attract other flies, so leaving flies in the box makes it an even better trap.  Once the flies are trapped, there are several ways in which you can dispose of them.  You can build your trap with a door in the outer wall.  If you want to kill the flies before you let them out, just pour very hot water on them inside the trap.  That will do the trick.