The concept behind this fly trap is to construct it as simply as possible using material that is junk. It is particularly hoped that this may be a way of using discarded pop and drinking water bottles.
Two preferably identical clear plastic bottles. The larger the better, they can be smooth or corrugated. One of the bottles should still have its screw top.
One smaller plastic bottle, this should be smooth plastic.ref>br /> A small quantity of black or dark paint.
Stanley or other sharp knife.
A small piece of string.
A pencil or other pointed instrument to make a small hole in the plastic bottle.
Method of assembly
One of the bottles is the bait bottle the other is the trap bottle the smaller bottle is used to cut out the trap tube.
The Bait bottle
If the paint is very thick it may need diluting. Pour the equivalent of a tablespoon of paint into this bottle, if possible do not let it run down the side; roll the bottle so that the lower third is painted on the inside. Leave it to dry.
The Trap bottle
Cut the bottom out of this. Make the cut just below where the bottle tapers into the base. Now make 8 slits upwards from where the base has been cut off. If the lower end of the bottle is corrugated, make the slits in the valleys. It should now be possible to push the trap bottle over the top of the trap bottle and make a tight fit. If at a later stage the splits in the side you have cut tend to tear further upwards this can be prevented by gluing small squares of plastic. Alternatively a ring of plastic is cut obliquely from another bottle of the same size, this can then be slipped over the bottle to prevent the cuts spreading upwards.
If the flytrap is to be hung introduce a small piece of string under the screw top, screwing the top on tightly.
The Trap Tube
This is a piece of plastic cut from the body of the smaller bottle. Cut a piece of bottle 8 cms
by 8 cms. Cut small slits in the bottom and bend these out as shown in the diagram. Now roll it around a pencil, wrap a piece of string around it and place it in hot water (three-quarters boiling one-quarter cold.) Remove the string, it should keep its shape. Make a hole in the screw top as follows. Hold it over a candle, the plastic will darken and soften. Push a pencil through and enlarge the hole. Push your tube up and through this hole and the frill you cut should now be pinched between the bottle top and the cap when it is screwed on to the bait bottle.
The Bait bottle
The paint in this should now be dry. Cut two half circles half way down the painted part at opposite sides of the bottle, the curve of the circle should be upwards, now bend the flap produced outwards and force them down so that they remain open. These are the entry ports for the flies, as well as putting bait in the bottom of the bait bottle put some on these turned down flaps to attract the flies.
The Fly Bait
Various baits have been used. Chicken entrails seem satisfactory but tend to dry up. Apparently flies like the smell produced by placing 250 gms of yeast in a litre of water and after two days adding 6 grams of Ammonium Carbonate (available from garden centres). Amongst the Maasai a mixture of goat dung and cows urine is effective.
(This design is preliminary. Further simplification and improvement must depend on field trials. It would be good to hear of alternative, locally available bait. Unfortunately the author has no access to large fly populations!!)